Ha ocurrido un error, por favor, comuniquelo en este momento

Query: SELECT * FROM categorias WHERE id=
Query Num: 3
Mysql Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 6
Mysql Error NO: 1064

Ha ocurrido un error, por favor, comuniquelo en este momento

Query: SELECT * FROM subcategorias WHERE id=
Query Num: 4
Mysql Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 6
Mysql Error NO: 1064