POSTGRESQL 处理隐行转换
问题背景: 两张表需要做关联,但A表的字段是INT类型, 而B表的是VARCHAR类型。 模拟: rocket2_i5=# create table t_int(id int4); CREATE TABLE rocket2_i5=# create table t_var(id varchar(9)); CREATE TABLE rocket2_i5=# insert into t_int values(1); INSERT 0 1 rocket2_i5=# insert into t_var values('1'); INSERT 0 1 rocket2_i5=# select * from t_int a inner join t_var b on a.id=b.id; ERROR: operator does not exist: integer = character varying LINE 1: select * from t_int a inner join t_var b on a.id=b.id; HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. 解决办法, 使用CAST函数: rocket2_i5=# select * from t_int a inner join t_var b on a.id=cast(b.id as int); id | id ----+---- 1 | 1 (1 row) rocket2_i5=# select * from t_int a inner join t_var b on cast(a.id as varchar)=b.id; id | id ----+---- 1 | 1 (1 row)