MyCATApache/Mycat-Server · error · IllegalArgumentException

not a query sql statement

Error message

not a query sql statement

What it means

MongoSQLParser.query() requires the parsed Druid AST to be a SQLSelectStatement; anything else (INSERT, UPDATE, DELETE, DDL, etc.) triggers IllegalArgumentException("not a query sql statement"). Only SELECT statements can be translated into a MongoDB find query by this parser.

Solutions

1. Only send SELECT statements down the query() path; route writes through executeUpdate/InsertData
2. Verify the SQL string actually parses as a Druid SQLSelectStatement (no trailing semicolon issues, no vendor-specific syntax)
3. Catch IllegalArgumentException around query() and redirect non-select statements to the update path
4. Pre-parse with Druid's SQLUtils to confirm statement type before calling query()

Example fix

// before
MongoData data = parser.query(); // throws for non-SELECT

// after
if (parser.getStatement() instanceof SQLSelectStatement) {
    MongoData data = parser.query();
} else {
    int affected = parser.executeUpdate();
}

SQLStatement stmt = SQLUtils.parseStatements(sql, dbType).get(0);
if (!(stmt instanceof SQLSelectStatement)) {
    // route to update path instead of query()
}

boolean isQuery(SQLStatement statement) {
    return statement instanceof SQLSelectStatement;
}

try {
    MongoData data = parser.query();
} catch (IllegalArgumentException e) {
    if ("not a query sql statement".equals(e.getMessage())) {
        // re-dispatch via executeUpdate or reject the statement type
    } else {
        throw e;
    }
}

When it happens

Trigger: Passing a non-SELECT SQL string (INSERT/UPDATE/DELETE/SHOW/etc.) through a path that calls MongoSQLParser.query(), e.g. executing an INSERT or UPDATE via the query/read path of the MongoDB JDBC handler.

Common situations: Client sends an UPDATE or INSERT statement but the MyCat route sends it to the MongoDB backend handler that always invokes query(); SQL dialect differences make Druid parse the statement as non-select (e.g. 'SELECT ... INTO'); test harness passing arbitrary SQL.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• number of columns error
• number of values and columns have to match
• not where of sql
• like SQL error
• Can't identify the operation of of where

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/f66653f5a1ecf020. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/backend/jdbc/mongodb/MongoSQLParser.java:66

	        return parser.parseStatement();
	     }
	     catch (Exception e)
	     {
	         LOGGER.error("MongoSQLParser.parserError", e);
	    }
	     throw new MongoSQLException.ErrorSQL(s);
	   }	
	
	public  void setParams(List params)
	   {
	     this._pos = 1;
	     this._params = params;
	   }
	   
	public MongoData query() throws MongoSQLException{
        if (!(statement instanceof SQLSelectStatement)) {
        	//return null;
        	throw new IllegalArgumentException("not a query sql statement");
        }
        MongoData mongo=new MongoData();
        DBCursor c=null;
        SQLSelectStatement selectStmt = (SQLSelectStatement)statement;
        SQLSelectQuery sqlSelectQuery =selectStmt.getSelect().getQuery();	
        int icount=0;
		if(sqlSelectQuery instanceof MySqlSelectQueryBlock) {
			MySqlSelectQueryBlock mysqlSelectQuery = (MySqlSelectQueryBlock)selectStmt.getSelect().getQuery();
			
			BasicDBObject fields = new BasicDBObject();
			//显示的字段
			for(SQLSelectItem item : mysqlSelectQuery.getSelectList()) {
				//System.out.println(item.toString());
				if (!(item.getExpr() instanceof SQLAllColumnExpr)) {
					if (item.getExpr() instanceof SQLAggregateExpr) {
						SQLAggregateExpr expr =(SQLAggregateExpr)item.getExpr();
						if (expr.getMethodName().equals("COUNT")) {
						   icount=1;

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