PostgreSQL 声明未命名行

Question

我使用以下选择语句来检索我需要处理的列数据：

SELECT c.table_schema, c.table_name, c.column_name, c.column_default, c.data_type, c.udt_name,
    ccu.table_name AS foreign_table_name,
    ccu.column_name AS foreign_column_name
FROM information_schema.columns AS c
    LEFT JOIN information_schema.key_column_usage AS kcu
        ON c.table_name = kcu.table_name AND c.column_name = kcu.column_name
    LEFT JOIN information_schema.constraint_column_usage as ccu
        ON kcu.constraint_name = ccu.constraint_name
WHERE c.table_name = 'mytable'

现在我需要遍历这个 select 语句的结果。我是这样做的：

CREATE OR REPLACE FUNCTION public.myfunction(tableName CHARACTER VARYING(18), rows NUMERIC(10))
RETURNS VOID AS $BODY$
DECLARE
  r ( table_schema varchar,
    table_name varchar,
    column_name varchar,
    column_default varchar,
    data_type varchar,
    udt_name varchar,
    foreign_table_name varchar,
    foreign_column_name varchar );
BEGIN
  FOR r IN (SELECT c.table_schema, c.table_name, c.column_name, c.column_default, c.data_type, c.udt_name,
                ccu.table_name AS foreign_table_name,
                ccu.column_name AS foreign_column_name
            FROM information_schema.columns AS c
                LEFT JOIN information_schema.key_column_usage AS kcu
                    ON c.table_name = kcu.table_name AND c.column_name = kcu.column_name
                LEFT JOIN information_schema.constraint_column_usage as ccu
                    ON kcu.constraint_name = ccu.constraint_name
            WHERE c.table_name = tableName) LOOP

  -- My plpgsql

  END LOOP;
  RETURN;
END;
$BODY$ LANGUAGE plpgsql VOLATILE;

如您所见，我通过命名列名和列类型来声明行r。哪个不起作用，我收到以下错误消息：ERROR: syntax error at or near "(" Position: 615 Where: invalid type name "( table_schema varchar, table_name varchar, column_name varchar, column_default varchar, data_type varchar, udt_name varchar, foreign_table_name varchar, foreign_column_name varchar )"

我还尝试将varchar 更改为information_schema.sql_identifier 和information_schema.character_data，它们是我要读取的列的information_schema 中的对象类型。

我是在声明正确的行和/或我应该使用不同的方法来循环具有多个连接的 select 语句吗？

Answer 1

如果你使用记录可能很简单

DECLARE
      r        record;
BEGIN
      FOR r IN select * from information_schema.columns
      LOOP
             ...

      END LOOP;