Basic SQL Parsing
This tutorial covers the essentials of parsing various SQL statements and extracting key information using General SQL Parser.
🎯 Objectives
- Parse SELECT, INSERT, UPDATE, DELETE statements
- Extract table names, column names, and conditions
- Work with complex queries involving JOINs and subqueries
- Handle different SQL statement types
- Apply best practices for SQL parsing
📋 Prerequisites
⏱️ Time Required
Approximately 45 minutes
📝 Step-by-Step Guide
1. Parsing SELECT Statements
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48 | // com.example.gsptutorial.BasicParsing
import gudusoft.gsqlparser.TGSqlParser;
import gudusoft.gsqlparser.EDbVendor;
import gudusoft.gsqlparser.stmt.TSelectSqlStatement;
import gudusoft.gsqlparser.nodes.TResultColumnList;
import gudusoft.gsqlparser.nodes.TTableList;
import gudusoft.gsqlparser.nodes.TWhereClause;
public class BasicSelectParsing {
public static void main(String[] args) {
TGSqlParser parser = new TGSqlParser(EDbVendor.dbvoracle);
parser.sqltext = "SELECT e.name, d.department_name " +
"FROM employees e JOIN departments d ON e.dept_id = d.id " +
"WHERE e.salary > 50000 AND d.location = 'New York'";
if (parser.parse() == 0) {
TSelectSqlStatement selectStmt = (TSelectSqlStatement) parser.sqlstatements.get(0);
System.out.println("Columns:");
TResultColumnList columns = selectStmt.getResultColumnList();
for (int i = 0; i < columns.size(); i++) {
System.out.println(" - " + columns.getResultColumn(i).getExpr().toString());
}
System.out.println("\nTables:");
TTableList tables = selectStmt.tables;
for (int i = 0; i < tables.size(); i++) {
System.out.println(" - " + tables.getTable(i).getFullName() +
(tables.getTable(i).getAliasClause() != null ?
" AS " + tables.getTable(i).getAliasName() : ""));
}
System.out.println("\nJoin Conditions:");
if (selectStmt.getjoins() != null){
for(int i=0; i<selectStmt.getjoins().size();i++){
System.out.println(" - " + selectStmt.getjoins().getJoin(i).getOnCondition().toString());
}
}
System.out.println("\nWHERE Clause:");
TWhereClause where = selectStmt.getWhereClause();
if (where != null) {
System.out.println(" " + where.getCondition().toString());
}
}
}
}
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2. Parsing INSERT Statements
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35 | // com.example.gsptutorial.BasicParsing
import gudusoft.gsqlparser.TGSqlParser;
import gudusoft.gsqlparser.EDbVendor;
import gudusoft.gsqlparser.stmt.TInsertSqlStatement;
import gudusoft.gsqlparser.nodes.TObjectNameList;
import gudusoft.gsqlparser.nodes.TMultiTargetList;
public class BasicInsertParsing {
public static void main(String[] args) {
TGSqlParser parser = new TGSqlParser(EDbVendor.dbvoracle);
parser.sqltext = "INSERT INTO customers (id, name, email) VALUES (1, 'John Doe', 'john.doe@example.com')";
if (parser.parse() == 0) {
TInsertSqlStatement insertStmt = (TInsertSqlStatement) parser.sqlstatements.get(0);
System.out.println("Target Table: " + insertStmt.getTargetTable().getFullName());
System.out.println("\nColumns:");
TObjectNameList columns = insertStmt.getColumnList();
if (columns != null) {
for (int i = 0; i < columns.size(); i++) {
System.out.println(" - " + columns.getObjectName(i).toString());
}
}
System.out.println("\nValues:");
TMultiTargetList values = insertStmt.getValues();
if (values != null && values.get(0) != null) {
for (int i = 0; i < values.get(0).getColumnList().size(); i++) {
System.out.println(" - " + values.get(0).getColumnList().getResultColumn(i).toString());
}
}
}
}
}
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✅ Summary
In this tutorial, you learned how to:
- Parse various SQL statement types (SELECT, INSERT, UPDATE, DELETE).
- Extract key information like table names, column names, and conditions.
- Handle complex queries with JOINs and subqueries.
What's Next?