diff --git a/tools/automatic_query_fixer/.gitattributes b/tools/automatic_query_fixer/.gitattributes
new file mode 100644
index 000000000..00a51aff5
--- /dev/null
+++ b/tools/automatic_query_fixer/.gitattributes
@@ -0,0 +1,6 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# These are explicitly windows files and should use crlf
+*.bat           text eol=crlf
+
diff --git a/tools/automatic_query_fixer/.gitignore b/tools/automatic_query_fixer/.gitignore
new file mode 100644
index 000000000..1fd477c43
--- /dev/null
+++ b/tools/automatic_query_fixer/.gitignore
@@ -0,0 +1,16 @@
+.gradle
+**/build/
+!src/**/build/
+.idea
+
+# Ignore Gradle GUI config
+gradle-app.setting
+
+# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
+!gradle-wrapper.jar
+
+# Cache of project
+.gradletasknamecache
+
+# # Work around https://youtrack.jetbrains.com/issue/IDEA-116898
+# gradle/wrapper/gradle-wrapper.properties
\ No newline at end of file
diff --git a/tools/automatic_query_fixer/build.gradle b/tools/automatic_query_fixer/build.gradle
new file mode 100644
index 000000000..83c06cf7d
--- /dev/null
+++ b/tools/automatic_query_fixer/build.gradle
@@ -0,0 +1,45 @@
+plugins {
+    id 'java'
+    id 'application'
+}
+
+group 'com.google.cloud.bigquery.utils'
+version '1.0-SNAPSHOT'
+
+
+
+application {
+    mainClassName = "com.google.cloud.bigquery.utils.auto_query_fixer.Application"
+}
+
+repositories {
+    mavenCentral()
+    flatDir {
+        dirs 'libs'
+    }
+
+}
+
+dependencies {
+
+    compileOnly 'org.projectlombok:lombok:1.18.12'
+    annotationProcessor 'org.projectlombok:lombok:1.18.12'
+    implementation 'org.apache.calcite.avatica:avatica-core:1.17.0'
+    implementation "org.apache.commons:commons-lang3:3.1"
+    // google flogger dependencies
+    compile group: 'com.google.flogger', name: 'flogger', version: '0.1'
+    compile 'com.google.flogger:flogger-system-backend:0.4'
+
+    // local jar
+    implementation name: 'calcite-babel-1.23.0-SNAPSHOT'
+    implementation name: 'calcite-core-1.23.0-SNAPSHOT'
+    implementation name: 'calcite-linq4j-1.23.0-SNAPSHOT'
+    //dependency from local jar
+    compile 'com.google.guava:guava:23.5-jre'
+    compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.25'
+    compile 'org.slf4j:slf4j-simple:1.7.25'
+
+    testCompileOnly 'org.projectlombok:lombok:1.18.12'
+    testAnnotationProcessor 'org.projectlombok:lombok:1.18.12'
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+}
diff --git a/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.jar b/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 000000000..f3d88b1c2
Binary files /dev/null and b/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.properties b/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 000000000..64d92ee58
--- /dev/null
+++ b/tools/automatic_query_fixer/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Thu Jun 25 02:01:57 UTC 2020
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-all.zip
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
diff --git a/tools/automatic_query_fixer/gradlew b/tools/automatic_query_fixer/gradlew
new file mode 100755
index 000000000..2fe81a7d9
--- /dev/null
+++ b/tools/automatic_query_fixer/gradlew
@@ -0,0 +1,183 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"
diff --git a/tools/automatic_query_fixer/gradlew.bat b/tools/automatic_query_fixer/gradlew.bat
new file mode 100644
index 000000000..9618d8d96
--- /dev/null
+++ b/tools/automatic_query_fixer/gradlew.bat
@@ -0,0 +1,100 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/tools/automatic_query_fixer/libs/calcite-babel-1.23.0-SNAPSHOT.jar b/tools/automatic_query_fixer/libs/calcite-babel-1.23.0-SNAPSHOT.jar
new file mode 100644
index 000000000..cbb42fe82
Binary files /dev/null and b/tools/automatic_query_fixer/libs/calcite-babel-1.23.0-SNAPSHOT.jar differ
diff --git a/tools/automatic_query_fixer/libs/calcite-core-1.23.0-SNAPSHOT.jar b/tools/automatic_query_fixer/libs/calcite-core-1.23.0-SNAPSHOT.jar
new file mode 100644
index 000000000..2e20949d8
Binary files /dev/null and b/tools/automatic_query_fixer/libs/calcite-core-1.23.0-SNAPSHOT.jar differ
diff --git a/tools/automatic_query_fixer/libs/calcite-linq4j-1.23.0-SNAPSHOT.jar b/tools/automatic_query_fixer/libs/calcite-linq4j-1.23.0-SNAPSHOT.jar
new file mode 100644
index 000000000..7f093116f
Binary files /dev/null and b/tools/automatic_query_fixer/libs/calcite-linq4j-1.23.0-SNAPSHOT.jar differ
diff --git a/tools/automatic_query_fixer/settings.gradle b/tools/automatic_query_fixer/settings.gradle
new file mode 100644
index 000000000..f2b0bcef6
--- /dev/null
+++ b/tools/automatic_query_fixer/settings.gradle
@@ -0,0 +1,10 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ *
+ * Detailed information about configuring a multi-project build in Gradle can be found
+ * in the user manual at https://docs.gradle.org/6.1.1/userguide/multi_project_builds.html
+ */
+
+rootProject.name = 'AutomaticQueryFixer'
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/BigQueryParserFactory.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/BigQueryParserFactory.java
new file mode 100644
index 000000000..c7a24e2ba
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/BigQueryParserFactory.java
@@ -0,0 +1,74 @@
+package com.google.cloud.bigquery.utils.queryfixer;
+
+import org.apache.calcite.avatica.util.Casing;
+import org.apache.calcite.avatica.util.Quoting;
+import org.apache.calcite.sql.parser.SqlParser;
+import org.apache.calcite.sql.parser.SqlParserImplFactory;
+import org.apache.calcite.sql.parser.babel.SqlBabelParserImpl;
+import org.apache.calcite.sql.validate.SqlConformance;
+import org.apache.calcite.sql.validate.SqlConformanceEnum;
+import org.apache.calcite.util.SourceStringReader;
+
+import java.io.Reader;
+
+/**
+ * A factory to generate parsers. The fault generated parser is Babel Parser with BigQuery dialect.
+ * */
+public class BigQueryParserFactory {
+
+  private final SqlParserImplFactory factory;
+  private final Quoting quoting = Quoting.BACK_TICK;
+  private final Casing unquotedCasing = Casing.TO_UPPER;
+  private final Casing quotedCasing = Casing.UNCHANGED;
+  private final SqlConformance conformance = SqlConformanceEnum.DEFAULT;
+  private final SqlParser.Config parserConfig;
+
+  /**
+   * Default initialization with the Babel Parser factory.
+   * */
+  public BigQueryParserFactory() {
+    factory = SqlBabelParserImpl.FACTORY;
+    this.parserConfig = buildConfig();
+  }
+
+  /**
+   * Initialization with customized factory
+   * @param factory customized factory */
+  public BigQueryParserFactory(SqlParserImplFactory factory) {
+    this.factory = factory;
+    this.parserConfig = buildConfig();
+  }
+
+  /**
+   * Get the parser parsing the input query.
+   * @param sql query to parse
+   * @return a parser loaded with the query
+   */
+  public SqlParser getParser(String sql) {
+    return getParser(new SourceStringReader(sql));
+  }
+
+  /**
+   * Get the config of the parser factory
+   * @return parser config
+   */
+  public SqlParser.Config getParserConfig() {
+    return parserConfig;
+  }
+
+  protected SqlParser getParser(Reader source) {
+    return SqlParser.create(source, parserConfig);
+  }
+
+  private SqlParser.Config buildConfig() {
+    final SqlParser.ConfigBuilder configBuilder =
+        SqlParser.configBuilder()
+            .setParserFactory(factory)
+            .setQuoting(quoting)
+            .setUnquotedCasing(unquotedCasing)
+            .setQuotedCasing(quotedCasing)
+            .setConformance(conformance);
+    return configBuilder.build();
+  }
+}
+
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryFixerMain.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryFixerMain.java
new file mode 100644
index 000000000..8be498d3e
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryFixerMain.java
@@ -0,0 +1,19 @@
+package com.google.cloud.bigquery.utils.queryfixer;
+
+import com.google.common.flogger.FluentLogger;
+
+public class QueryFixerMain {
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  public static void main(String[] args) {
+
+    if (args.length == 0) {
+      logger.atInfo().log("not enough arguments");
+      return;
+    }
+
+    String query = args[0];
+    // TODO: this should act as a command line, which will be developed after the fixer component is ready.
+  }
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenService.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenService.java
new file mode 100644
index 000000000..3352b08a4
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenService.java
@@ -0,0 +1,132 @@
+package com.google.cloud.bigquery.utils.queryfixer;
+
+import org.apache.calcite.sql.parser.babel.SqlBabelParserImpl;
+import org.apache.calcite.sql.parser.babel.Token;
+import org.apache.calcite.util.SourceStringReader;
+import org.apache.commons.lang3.tuple.Pair;
+
+import com.google.cloud.bigquery.utils.queryfixer.entity.IToken;
+import com.google.cloud.bigquery.utils.queryfixer.entity.TokenImpl;
+
+import lombok.AllArgsConstructor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A service provides methods for query and token. It can be used to tokenize queries, find tokens based on
+ * positions, and modify a query in token-level.
+ * */
+@AllArgsConstructor
+public class QueryTokenService {
+
+  private final static String BackTickQuotingMode = "BTID";
+  private final BigQueryParserFactory parserFactory;
+
+  /**
+   * return a pair of tokens which is closed to a specific position at a query. The left returned token
+   * is left to the position, and the right returned token is at or right to the position.
+   * @param sql the input query
+   * @param line the line of the position.
+   * @param column the column of the position
+   * @return a pair of tokens.
+   */
+  public Pair<IToken, IToken> getNearbyTokens(String sql, int line, int column) {
+    IToken previous = null;
+
+    for (IToken token : getAllTokens(sql)) {
+      if (token.getBeginLine() >= line && token.getBeginCol() >= column) {
+        return Pair.of(previous, token);
+      }
+      previous = token;
+    }
+
+    return Pair.of(previous, previous);
+  }
+
+  /**
+   * tokenize a query and return all its tokens.
+   * @param sql the query to be tokenized
+   * @return a list of tokens of the query
+   */
+  public List<IToken> getAllTokens(String sql) {
+    List<IToken> tokens = new ArrayList<>();
+
+    // SqlBabelParserImpl has a token manager to tokenize the input query.
+    SqlBabelParserImpl parserImpl = (SqlBabelParserImpl) parserFactory.getParserConfig()
+        .parserFactory().getParser(new SourceStringReader(sql));
+    parserImpl.switchTo(BackTickQuotingMode);
+
+    Token token;
+    final int EndKind = 0;
+    // Token kind means the category: it could be some keywords, identifier, literals, and etc.
+    // The end of a token stream is end token, whose value is zero.
+    while ((token = parserImpl.getNextToken()).kind != EndKind) {
+      tokens.add(new TokenImpl(token));
+    }
+
+    return tokens;
+  }
+
+  /**
+   * replace a token of a query and return the new query.
+   * @param sql the query whose token is to be replaced
+   * @param token the token to be replaced
+   * @param identifier the identifier the token is placed to.
+   * @return the replaced query
+   */
+  public String replaceToken(String sql, IToken token, String identifier) {
+    String[] lines = sql.split("\n");
+    validateToken(lines, token);
+
+    // The token's line and column number are 1-index,
+    // but the array and string index start with 0.
+    String line = lines[token.getBeginLine() - 1];
+    line = replaceStringBetweenIndex(line, token.getBeginCol() - 1, token.getEndCol(), identifier);
+    lines[token.getBeginLine() - 1] = line;
+
+    return String.join("\n", lines);
+  }
+
+  /**
+   * insert an identifier before a token and return the new query.
+   * @param sql the query to be inserted
+   * @param token the token to be inserted in front
+   * @param identifier the inserted identifier
+   * @return the inserted query
+   */
+  public String insertBeforeToken(String sql, IToken token, String identifier) {
+    return replaceToken(sql, token, identifier + " " + token.getImage());
+  }
+
+  /**
+   * delete a token from a query and return the new query.
+   * @param sql the query whose token is to be deleted
+   * @param token the token to be deleted
+   * @return the modified query
+   */
+  public String deleteToken(String sql, IToken token) {
+    return replaceToken(sql, token, "");
+  }
+
+  private void validateToken(String[] lines, IToken token) {
+    if (token.getBeginLine() != token.getEndLine()) {
+      throw new IllegalArgumentException("Illegal Token");
+    }
+
+    if (token.getEndLine() > lines.length) {
+      throw new IllegalArgumentException("the end line of token exceeds the total length of query");
+    }
+  }
+
+  /**
+   * replace a substring of a string to a new one. the replacing range is replaced as [startIndex, endIndex),
+   * i.e. the endIndex is excluded.
+   */
+  private String replaceStringBetweenIndex(String old, int startIndex, int endIndex, String replacingPart) {
+    StringBuilder builder = new StringBuilder(old);
+    builder.replace(startIndex, endIndex, replacingPart);
+    return builder.toString();
+  }
+
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/ChoiceRequest.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/ChoiceRequest.java
new file mode 100644
index 000000000..0d108459e
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/ChoiceRequest.java
@@ -0,0 +1,28 @@
+package com.google.cloud.bigquery.utils.queryfixer.entity;
+
+import lombok.Data;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A request to ask users to choose/confirm an option to fix the query. The request contains error
+ * position and a list of fix options.
+ *
+ * @see package com.google.cloud.bigquery.utils.auto_query_fixer.entity.FixOption
+ */
+@Data
+public class ChoiceRequest {
+
+  Object errPos;
+  List<FixOption> fixOptions;
+
+  /** create a choiceRequest and initialize its fixOptions List. */
+  public ChoiceRequest() {
+    fixOptions = new ArrayList<>();
+  }
+
+  public void addChoice(FixOption fixOption) {
+    fixOptions.add(fixOption);
+  }
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixOption.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixOption.java
new file mode 100644
index 000000000..67c510d06
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixOption.java
@@ -0,0 +1,13 @@
+package com.google.cloud.bigquery.utils.queryfixer.entity;
+
+import lombok.Value;
+
+/**
+ * An option to fix an error of a query. It contains the description on how to fix the error and the
+ * query after fixing.
+ */
+@Value
+public class FixOption {
+  String description;
+  String fixedQuery;
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixResult.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixResult.java
new file mode 100644
index 000000000..e5e5d0125
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/FixResult.java
@@ -0,0 +1,22 @@
+package com.google.cloud.bigquery.utils.queryfixer.entity;
+
+
+import lombok.Data;
+
+/**
+ * A result on fixing a query. It has three states: SUCCESS, FAIL, REQUEST_RESPONSE.
+ * SUCCESS means the fixed query is error prone. FAIL means the query contains error(s) and cannot be fixed.
+ * REQUEST_RESPONSE means the auto fixer needs a response to perform next fixing.
+ * */
+@Data
+public class FixResult {
+
+  private Status status;
+  private String output;
+  private String error;
+
+
+  private enum Status {
+    SUCCESS, FAIL, REQUEST_RESPONSE
+  }
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/IToken.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/IToken.java
new file mode 100644
index 000000000..75926ce28
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/IToken.java
@@ -0,0 +1,20 @@
+package com.google.cloud.bigquery.utils.queryfixer.entity;
+
+/**
+ * A interface for queries' tokens.
+ * */
+public interface IToken {
+
+  int getKind();
+
+  String getImage();
+
+  int getBeginLine();
+
+  int getBeginCol();
+
+  int getEndLine();
+
+  int getEndCol();
+
+}
diff --git a/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/TokenImpl.java b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/TokenImpl.java
new file mode 100644
index 000000000..5006d3ecc
--- /dev/null
+++ b/tools/automatic_query_fixer/src/main/java/com/google/cloud/bigquery/utils/queryfixer/entity/TokenImpl.java
@@ -0,0 +1,52 @@
+package com.google.cloud.bigquery.utils.queryfixer.entity;
+
+import org.apache.calcite.sql.parser.babel.Token;
+
+/**
+ * An implementation of token interface based on the Token class of Babel Calcite Parser.
+ * */
+public class TokenImpl implements IToken {
+
+  private final Token token;
+
+  public TokenImpl (Token token) {
+    this.token = token;
+  }
+
+  @Override public int getKind() {
+    return token.kind;
+  }
+
+  @Override public String getImage() {
+    return token.image;
+  }
+
+  @Override public int getBeginLine() {
+    return token.beginLine;
+  }
+
+  @Override public int getBeginCol() {
+    return token.beginColumn;
+  }
+
+  @Override public int getEndLine() {
+    return token.endLine;
+  }
+
+  @Override public int getEndCol() {
+    return token.endColumn;
+  }
+
+  // babel is a type of parser in Calcite, and this class uses its token for implementation.
+  public Token getBabelToken() {
+    return token;
+  }
+
+  @Override public String toString() {
+    return  String.format("%s [%d:%d]", token.image, token.beginLine, token.beginColumn);
+  }
+
+  //  public static TokenImpl newToken(int ofKind) {
+//    return new TokenImpl(Token.newToken(ofKind));
+//  }
+}
diff --git a/tools/automatic_query_fixer/src/test/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenServiceTest.java b/tools/automatic_query_fixer/src/test/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenServiceTest.java
new file mode 100644
index 000000000..dd50d5f1c
--- /dev/null
+++ b/tools/automatic_query_fixer/src/test/java/com/google/cloud/bigquery/utils/queryfixer/QueryTokenServiceTest.java
@@ -0,0 +1,74 @@
+package com.google.cloud.bigquery.utils.queryfixer;
+
+import org.apache.commons.lang3.tuple.Pair;
+
+import com.google.cloud.bigquery.utils.queryfixer.entity.IToken;
+
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class QueryTokenServiceTest {
+
+  private QueryTokenService createService() {
+    return new QueryTokenService(new BigQueryParserFactory());
+  }
+
+  @Test
+  public void convertSqlToTokens() {
+    QueryTokenService tokenService = createService();
+    String sql = "Select col from `d1.t1` Join\n" +
+        "t2 on d1.t1.id = t2.id\n" +
+        "where t1.col > 'val'";
+
+    List<IToken> tokens = tokenService.getAllTokens(sql);
+    for (IToken token : tokens) {
+      System.out.println(token);
+    }
+  }
+
+  @Test
+  public void testNearbyTokens() {
+    QueryTokenService tokenService = createService();
+    String sql = "Select col from t1 Join\n" +
+        "t2 on t1.id = t2.id\n" +
+        "where t1.col > 'val'";
+
+    Pair<IToken, IToken> tokenPair =  tokenService.getNearbyTokens(sql, 1, 12);
+    assertEquals("col", tokenPair.getLeft().getImage());
+    assertEquals("from", tokenPair.getRight().getImage());
+
+    tokenPair =  tokenService.getNearbyTokens(sql, 3, 1);
+    assertEquals("id", tokenPair.getLeft().getImage());
+    assertEquals("where", tokenPair.getRight().getImage());
+  }
+
+  @Test
+  public void modifyQuery() {
+    QueryTokenService tokenService = createService();
+    String sql = "Select col from t1 Join\n" +
+        "t2 on t1.id = t2.id\n" +
+        "where t1.col > 'val'";
+
+    String identifier = "Select Distinct";
+
+    IToken token =  tokenService.getNearbyTokens(sql, 1, 1).getRight();
+    String modifiedQuery =  tokenService.replaceToken(sql, token, identifier);
+    // modified: Select Distinct col
+    assertEquals(identifier, modifiedQuery.substring(0, identifier.length()));
+
+    identifier = "Distinct";
+    token =  tokenService.getNearbyTokens(sql, 1, 8).getRight();
+    modifiedQuery =  tokenService.insertBeforeToken(sql, token, identifier);
+    // modified: Select Distinct col
+    assertEquals(identifier, modifiedQuery.substring(7, 7 + identifier.length()));
+
+    token =  tokenService.getNearbyTokens(sql, 1, 8).getRight();
+    modifiedQuery =  tokenService.deleteToken(sql, token);
+    // modified: Select  from ...
+    assertEquals("from", modifiedQuery.substring(8, 12));
+  }
+
+}