PostgreSQL - 如何使用游标更改不同表列的长度

Question

我正在更改所有必要表的列长度，但我遇到了一些错误。

我正在使用PostgreSQL 10和pgAdmin4，但我看不到错误消息。

我猜，因为 pgAdmin 版本。首先，我无法声明CURSOR，我不知道为什么？我在甲骨文上取得了成功。

你能帮我解决这种情况吗？我的代码如下所示;

do $$
DECLARE
    modify_column_cursor CURSOR FOR 
        SELECT 'ALTER TABLE "schema_name"."' || C.TABLE_NAME || '" ALTER COLUMN'|| C.COLUMN_NAME||' varchar(128)'  as alter_sql, TABLE_NAME t_name, COLUMN_NAME c_name, 128 c_length FROM information_schema.columns c  WHERE column_name LIKE '%PROD_NUM' and TABLE_NAME not like '%STAGING%'  UNION
        SELECT 'ALTER TABLE "schema_name"."' || C.TABLE_NAME || '" ALTER COLUMN'|| C.COLUMN_NAME||' varchar(128)'  as alter_sql, TABLE_NAME t_name, COLUMN_NAME c_name, 128 c_length FROM information_schema.columns c  WHERE column_name LIKE '%PREV_PROD_NUM' and TABLE_NAME not like '%STAGING%';
        --.
        --.
        --.
    sql_stmt    VARCHAR(800);
    c_length    numeric;
    c_length_db numeric;
    flag        numeric := 0;
BEGIN
    --OPEN modify_column_cursor;
    for modify_column in modify_column_cursor LOOP
        raise notice 'asd : %', modify_column.ex_name;
        sql_stmt := 'SELECT character_maximum_length FROM information_schema.columns WHERE column_name = ''' || modify_column.c_name || ''' and table_name = ''' || modify_column.t_name || ''' and table_schema = ''schema_name''';
        EXECUTE sql_stmt INTO c_length_db;
        IF c_length_db > modify_column.c_length THEN
            sql_stmt := 'select max(length(' || modify_column.c_name || ')) from "schema_name".' || modify_column.t_name;
            EXECUTE sql_stmt INTO c_length;
            IF c_length > modify_column.c_length THEN
                flag := 1;
                raise notice '--------------INCONSISTENED FIELD FOUND---------------';
                raise notice '% - % - %   Not Ok!   Default field size in db: %', modify_column.t_name, modify_column.c_name, modify_column.c_length, c_length_db;
                raise notice '% - % - %   Not Ok!   Field has a data with length: %', modify_column.t_name, modify_column.c_name, modify_column.c_length, c_length;
                raise notice '-------------------------------------------------------';
                raise notice ' ';
            ELSE
                NULL;
            END IF;
        ELSE
            NULL;
        END IF;
    END LOOP;

    IF flag = 0 THEN
        FOR modify_column IN modify_column_cursor
        LOOP
            EXECUTE modify_column.alter_sql;
        END LOOP;
        raise notice ' ';
        raise notice '-----FIELDS ARE SUCCESSFULLY MODIFIED-----';
    ELSE
        raise notice ' ';
        raise notice '-----ERROR: SOME FIELDS ARE NOT SUITABLE TO ALTER-----';
    END IF;
end$$; 

Answer 1

我在PostgreSQL 11上，但如果我记得不错的话，它几乎是一样的。如果你想绝对使用循环来做到这一点，我纠正了你的代码并注入了一个调试表。

缺少空格和错误的光标声明。我只是骑上了它。

如果你愿意，你可以在postgresql上阅读这篇关于光标的优秀文章： http://www.postgresqltutorial.com/plpgsql-cursor/

do $$
DECLARE
    sql_stmt    VARCHAR(800);
    c_length    numeric;
    c_length_db numeric;
    flag        numeric := 0;
    modify_column record;
begin
    create table if not exists [your_schema_name].test (query varchar);
    for modify_column in 
        SELECT 'ALTER TABLE "'||[your_schema_name]||'"."' || C.TABLE_NAME || '" ALTER COLUMN '|| C.COLUMN_NAME||' varchar(128)'  as alter_sql
                , TABLE_NAME t_name
                , COLUMN_NAME c_name
                , 128 c_length 
        FROM information_schema.columns c  
        where table_schema = ''||[your_schema_name]||''
    LOOP
        --raise notice 'asd : %', modify_column.ex_name;
        sql_stmt := 'SELECT character_maximum_length FROM information_schema.columns WHERE column_name = ''' || modify_column.c_name || ''' and table_name = ''' || modify_column.t_name || ''' and table_schema = '''||[your_schema_name]||'''';
        insert into [your_schema_name].test values (sql_stmt);
       EXECUTE sql_stmt INTO c_length_db;
        IF c_length_db > modify_column.c_length THEN
            sql_stmt := 'select max(length(' || modify_column.c_name || ')) from "'||[your_schema_name]||'".' || modify_column.t_name;
            --EXECUTE sql_stmt INTO c_length;
            insert into [your_schema_name].test values (sql_stmt);
            IF c_length > modify_column.c_length THEN
                flag := 1;
                raise notice '--------------INCONSISTENED FIELD FOUND---------------';
                raise notice '% - % - %   Not Ok!   Default field size in db: %', modify_column.t_name, modify_column.c_name, modify_column.c_length, c_length_db;
                raise notice '% - % - %   Not Ok!   Field has a data with length: %', modify_column.t_name, modify_column.c_name, modify_column.c_length, c_length;
                raise notice '-------------------------------------------------------';
                raise notice ' ';
            ELSE
                NULL;
            END IF;
        ELSE
            NULL;
        END IF;
    END LOOP;

    IF flag = 0 THEN
        --FOR modify_column IN modify_column_cursor
       -- LOOP
       --     EXECUTE modify_column.alter_sql;
        --END LOOP;
        raise notice ' ';
        raise notice '-----FIELDS ARE SUCCESSFULLY MODIFIED-----';
    ELSE
        raise notice ' ';
        raise notice '-----ERROR: SOME FIELDS ARE NOT SUITABLE TO ALTER-----';
    END IF;
end;
$$;