SQL Statement Nodes¶

SQL Statement nodes represent the top-level operations in SQL commands. Each statement type has its own dedicated AST node class that contains the specific components and clauses relevant to that operation.

Overview¶

Statement nodes are the root nodes of parsed SQL commands. They inherit from TSqlStatement and provide methods to access their constituent parts like clauses, expressions, and table references.

Available Statement Types¶

Data Query Language (DQL)¶

SELECT Statement - TSelectSqlStatement
Query data from tables
Supports complex joins, subqueries, aggregations
Most commonly used statement type

Data Manipulation Language (DML)¶

INSERT Statement - TInsertSqlStatement
Insert new data into tables
Supports VALUES clauses and SELECT-based inserts
UPDATE Statement - TUpdateSqlStatement
Modify existing data in tables
Includes SET clauses and WHERE conditions
DELETE Statement - TDeleteSqlStatement
Remove data from tables
Supports conditional deletion with WHERE clauses

Data Definition Language (DDL)¶

CREATE Statement - TCreateSqlStatement
Create database objects (tables, views, indexes, etc.)
Database-specific variations supported
ALTER Statement - TAlterSqlStatement
Modify existing database objects
Add/drop columns, constraints, etc.
DROP Statement - TDropSqlStatement
Remove database objects
Cascade options supported

Common Properties¶

All statement nodes share these characteristics:

Property	Description	Access Method
`sqlstatementtype`	Type of SQL statement	`getSqlStatementType()`
`startToken`	First token in statement	`getStartToken()`
`endToken`	Last token in statement	`getEndToken()`
`sourceString`	Original SQL text	`toString()`

Usage Patterns¶

Identifying Statement Types¶

TSqlStatement stmt = parser.sqlstatements.get(0);
switch (stmt.getSqlStatementType()) {
    case sstselect:
        TSelectSqlStatement select = (TSelectSqlStatement) stmt;
        // Process SELECT statement
        break;
    case sstinsert:
        TInsertSqlStatement insert = (TInsertSqlStatement) stmt;
        // Process INSERT statement
        break;
    // ... other cases
}

Extracting Tables from Any Statement¶

public Set<String> getReferencedTables(TSqlStatement stmt) {
    final Set<String> tables = new HashSet<>();

    stmt.acceptChildren(new IElementVisitor() {
        public void visitElement(TParseTreeNode node) {
            if (node instanceof TTable) {
                TTable table = (TTable) node;
                tables.add(table.getTableName());
            }
        }
    });

    return tables;
}

Database-Specific Considerations¶

Some statements have database-specific variations:

SQL Server: MERGE statements, OUTPUT clauses
Oracle: MERGE statements, hierarchical queries with CONNECT BY
PostgreSQL: UPSERT with ON CONFLICT
MySQL: REPLACE statements, ON DUPLICATE KEY UPDATE