Sql >它还将保留列的数据类型。 id | Column1 | Column2 | Column3 ------------------------------------------------- 1 | Register1C1

>它还将保留列的数据类型。

id | Column1          | Column2     | Column3
-------------------------------------------------
1  | Register1C1      | Register1C2 | Register1C3

Id | ColumnName | Value
-----------------------------
1  | Column1    | Register1C1
1  | Column2    | Register1C2
1  | Column3    | Register1C3

SELECT id
    ,unnest(string_to_array('col1,col2,col3', ',')) col_name
    ,unnest(string_to_array(col1 || ',' || col2 || ',' || col3, ',')) val
FROM t

select string_agg(column_name,',') cols from information_schema.columns where
table_name='t' and column_name<>'id'

SELECT 'select id,unnest(string_to_array(''' || cols || ''','','')) col_name,unnest(string_to_array(' || cols1 || ','','')) val from t'
FROM (
        SELECT string_agg(column_name, ',') cols  -- here we'll get all the columns in table t
            ,string_agg(column_name, '||'',''||') cols1 
        FROM information_schema.columns
        WHERE table_name = 't'
            AND column_name <> 'id'
) tb;

    CREATE OR replace FUNCTION fn ()
RETURNS TABLE (
        id INT
        ,columname TEXT
        ,columnvalues TEXT
        ) AS $$

DECLARE qry TEXT;
BEGIN
    SELECT 'select id,unnest(string_to_array(''' || cols || ''','','')) col_name,unnest(string_to_array(' || cols1 || ','','')) val from t'
    INTO qry
    FROM (
        SELECT string_agg(column_name, ',') cols
            ,string_agg(column_name, '||'',''||') cols1
        FROM information_schema.columns
        WHERE table_name = 't'
            AND column_name <> 'id'
        ) tb;

    RETURN QUERY
    EXECUTE format(qry);
END;$$
LANGUAGE plpgsql

SELECT t.id, v.*
FROM   tbl t, LATERAL (
   VALUES
     ('col1', col1)
   , ('col2', col2)
   , ('col3', col3)
      -- etc.
   ) v(col, val);

SELECT t.id, v.col, v.val
FROM   tbl t, LATERAL (
   VALUES
     (1, 'col1', col1::text)
   , (2, 'col2', col2::text)
   , (3, 'col3', col3::text)
     -- etc.
   ) v(rank, col, val)
ORDER  BY t.id, v.rank;

SELECT t.id, v.*
FROM   tbl t, unnest('{col1,col2,col3}'::text[]
               , ARRAY[col1,col2,col3]) v(col, val);
           --  , ARRAY[col1::text,col2::text,col3::text]) v(col, val);

CREATE OR REPLACE FUNCTION f_transpose (_tbl regclass, VARIADIC _cols text[])
  RETURNS TABLE (id int, col text, val text) AS
$func$
BEGIN
   RETURN QUERY EXECUTE format(
     'SELECT t.id, v.* FROM %s t, unnest($1, ARRAY[%s]) v'
   , _tbl, array_to_string(_cols, '::text,') || '::text'))
-- , _tbl, array_to_string(_cols, ',')))  -- simple alternative for only text
   USING _cols;
END
$func$  LANGUAGE plpgsql;

SELECT * FROM f_transpose('table_name', 'column1', 'column2', 'column3');