postgresql - 如果 case-when-then-else 子句给出 ERROR: more than one row returned by a subquery used as an expression。在PostgreSQL中

Question

在触发以下查询时会给出错误：用作表达式的子查询返回的不止一行。

select case when (table_name_1.column_name = 'ABC')
then (select column_name_2 from table_name_2 where column_name_3='XYZ')
else table_name_1.column_name end as result from table_name_1 ;

标签： postgresqlsubquerycase-when