sql - POSTGRESQL:创建表作为选择特定类型的列

Question

我有一个包含混合类型数据(实数、整数、字符...)的表，但我只会恢复具有实数值的列。

我可以构造这个:

SELECT 'SELECT ' || array_to_string(ARRAY(
select 'o' || '.' || c.column_name 
from information_schema.columns as c
where table_name = 'final_datas'
and c.data_type = 'real'), ',') || ' FROM final_datas as o' As sqlstmt

这给出了:

"SELECT o.random,o.struct2d_pred2_num,o.pfam_num,o.transmb_num [...] FROM final_datas as o"

我想用这些列创建一个表。当然，这样做是行不通的:

create table table2 as (
SELECT 'SELECT ' || array_to_string(ARRAY(
select 'o' || '.' || c.column_name 
from information_schema.columns as c
where table_name = 'final_datas'
and c.data_type = 'real'), ',') || ' FROM final_datas as o' As sqlstmt
)

建议？

Answer 1

您需要将整个 CREATE TABLE 语句生成为动态 SQL:

SELECT 'CREATE TABLE table2 AS SELECT ' || array_to_string(ARRAY(
select 'o' || '.' || c.column_name 
from information_schema.columns as c
where table_name = 'final_datas'
and c.data_type = 'real'), ',') || ' FROM final_datas as o' As sqlstmt

结果可以用EXECUTE sqlstmt;运行