String sqlStr = "select 1 from dual where a=b";

PlainSelect select = (PlainSelect) CCJSqlParserUtil.parse(sqlStr);

SelectItem selectItem =
        select.getSelectItems().get(0);
Assertions.assertEquals(
        new LongValue(1)
        , selectItem.getExpression());

Table table = (Table) select.getFromItem();
Assertions.assertEquals("dual", table.getName());

EqualsTo equalsTo = (EqualsTo) select.getWhere();
Column a = (Column) equalsTo.getLeftExpression();
Column b = (Column) equalsTo.getRightExpression();
Assertions.assertEquals("a", a.getColumnName());
Assertions.assertEquals("b", b.getColumnName());

CCJSqlParser parser = new CCJSqlParser(
        "select * from mytable; select from; select * from mytable2" );
Statements statements = parser.withErrorRecovery().Statements();

// 3 statements, the failing one set to NULL
assertEquals(3, statements.size());
assertNull(statements.get(1));

// errors are recorded
assertEquals(1, parser.getParseErrors().size());

Statements statements = CCJSqlParserUtil.parseStatements(
        "select * from mytable; select from; select * from mytable2; select 4;"
        , parser -> parser.withUnsupportedStatements() );

// 4 statements with one Unsupported Statement holding the content
assertEquals(4, statements.size());
assertInstanceOf(UnsupportedStatement.class, statements.get(1));
assertEquals("select from", statements.get(1).toString());

// no errors records, because a statement has been returned
assertEquals(0, parser.getParseErrors().size());

// Define an Expression Visitor reacting on any Expression
// Overwrite the visit() methods for each Expression Class
ExpressionVisitorAdapter<Void> expressionVisitorAdapter = new ExpressionVisitorAdapter<>() {
    public <S> Void visit(EqualsTo equalsTo, S context) {
        equalsTo.getLeftExpression().accept(this, context);
        equalsTo.getRightExpression().accept(this, context);
        return null;
    }
    public <S> Void visit(Column column, S context) {
        System.out.println("Found a Column " + column.getColumnName());
        return null;
    }
};

// Define a Select Visitor reacting on a Plain Select invoking the Expression Visitor on the Where Clause
SelectVisitorAdapter<Void> selectVisitorAdapter = new SelectVisitorAdapter<>() {
    @Override
    public <S> Void visit(PlainSelect plainSelect, S context) {
        return plainSelect.getWhere().accept(expressionVisitorAdapter, context);
    }
};

// Define a Statement Visitor for dispatching the Statements
StatementVisitorAdapter<Void> statementVisitor = new StatementVisitorAdapter<>() {
    public <S> Void visit(Select select, S context) {
        return select.getSelectBody().accept(selectVisitorAdapter, context);
    }
};

String sqlStr="select 1 from dual where a=b";
Statement stmt = CCJSqlParserUtil.parse(sqlStr);

// Invoke the Statement Visitor without a context
stmt.accept(statementVisitor, null);

// find in Statements
String sqlStr = "select * from A left join B on A.id=B.id and A.age = (select age from C)";
Set<String> tableNames = TablesNamesFinder.findTables(sqlStr);
assertThat( tableNames ).containsExactlyInAnyOrder("A", "B", "C");

// find in Expressions
String exprStr = "A.id=B.id and A.age = (select age from C)";
tableNames = TablesNamesFinder.findTablesInExpression(exprStr);
assertThat( tableNames ).containsExactlyInAnyOrder("A", "B", "C");

String expectedSQLStr = "SELECT 1 FROM dual t WHERE a = b";

// Step 1: generate the Java Object Hierarchy for
Table table = new Table().withName("dual").withAlias(new Alias("t", false));

Column columnA = new Column().withColumnName("a");
Column columnB = new Column().withColumnName("b");
Expression whereExpression =
        new EqualsTo().withLeftExpression(columnA).withRightExpression(columnB);

PlainSelect select = new PlainSelect().addSelectItem(new LongValue(1))
        .withFromItem(table).withWhere(whereExpression);

// Step 2a: Print into a SQL Statement
Assertions.assertEquals(expectedSQLStr, select.toString());

// Step 2b: De-Parse into a SQL Statement
StringBuilder builder = new StringBuilder();
StatementDeParser deParser = new StatementDeParser(builder);
deParser.visit(select);

Assertions.assertEquals(expectedSQLStr, builder.toString());

String sqlStr="select 1 from [sample_table] where [a]=[b]";

// T-SQL Square Bracket Quotation
Statement stmt = CCJSqlParserUtil.parse(
        sqlStr
        , parser -> parser
            .withSquareBracketQuotation(true)
);

// Set Parser Timeout to 6000 ms
Statement stmt1 = CCJSqlParserUtil.parse(
        sqlStr
        , parser -> parser
            .withSquareBracketQuotation(true)
            .withTimeOut(6000)
);

// Allow Complex Parsing (which allows nested Expressions, but is much slower)
Statement stmt2 = CCJSqlParserUtil.parse(
        sqlStr
        , parser -> parser
            .withSquareBracketQuotation(true)
            .withAllowComplexParsing(true)
            .withTimeOut(6000)
);

// Allow Back-slash escaping
sqlStr="SELECT ('\\'Clark\\'', 'Kent')";
Statement stmt2 = CCJSqlParserUtil.parse(
        sqlStr
        , parser -> parser
            .withBackslashEscapeCharacter(true)
);