查询 mysql中 所有的 非空记录字段

mysql 查询 所有的 非空记录字段

CREATE DEFINER=`root`@`%` PROCEDURE `find_actual_non_null_columns`(IN db_name VARCHAR(255))
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE tab_name VARCHAR(255);
    DECLARE col_name VARCHAR(255);
    DECLARE cur CURSOR FOR 
        SELECT TABLE_NAME, COLUMN_NAME
        FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_SCHEMA = db_name;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    DROP TEMPORARY TABLE IF EXISTS temp_non_null_columns;
    CREATE TEMPORARY TABLE temp_non_null_columns (
        table_name VARCHAR(255),
        column_name VARCHAR(255)
    );

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO tab_name, col_name;
        IF done THEN
            LEAVE read_loop;
        END IF;

        -- 检查该字段是否有非空记录（非全是null）
        SET @query = CONCAT(
            'SELECT COUNT(*) INTO @non_null_count FROM `', db_name, '`.`', tab_name, '` WHERE `', col_name, '` IS NOT NULL AND `', col_name, '` != '''''
        );

        PREPARE stmt FROM @query;
        EXECUTE stmt;
        DEALLOCATE PREPARE stmt;

        -- 如果有非空记录，说明该字段非全是null
        IF @non_null_count > 0 THEN
            INSERT INTO temp_non_null_columns VALUES (tab_name, col_name);
        END IF;
    END LOOP;

    CLOSE cur;

    SELECT 
        table_name AS table_name,
        column_name AS column_name
    FROM temp_non_null_columns
    ORDER BY table_name, column_name;

END

调用

CALL find_actual_non_null_columns('schy');