Semi-connection & Anti-connection #

DBPlusEngine currently supports semi-connection in the following forms:

SELECT * FROM t_order WHERE order_id IN (1, 2, 3);

It does not support semi-connection with sharding tables in subqueries.

Note: the error is usually caused by not rewriting the table name, causing the database to not find the table and return an error. If the table name does not need to be rewritten, it can be executed, but the returned result is incorrect.

SELECT * FROM t_order WHERE EXISTS (SELECT * FROM t_order_item);

DBPlusEngine currently supports anti-connection in the following forms:

SELECT * FROM t_order WHERE order_id NOT IN (1, 2, 3);

It does not support anti-connection with sharding tables in subqueries.

Note: the error is usually caused by not rewriting the table name, causing the database to not find the table and return an error. If the table name does not need to be rewritten, it can be executed, but the returned result is incorrect.

SELECT * FROM t_order WHERE NOT EXISTS (SELECT * FROM t_order_item);