PostgreSQL如何判断字段是否存在
方法一：
select count(*) from information_schema.columns WHERe table_schema = 'table_schema' and table_name = 'table_name' and column_name = 'column_name';
方法二：
select * from information_schema.columns WHERe table_schema = 'table_schema' and table_name = 'table_name' and column_name = 'column_name';
补充：
判断表是否存在：
select count (*) from information_schema.tables WHERe table_schema = 'table_schema' and table_name = 'table_name'; select * from information_schema.tables WHERe table_schema = 'table_schema' and table_name = 'table_name';
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