我正在尝试编写一个脚本，它采用如下简单查询：
select col1, count(*)
from city
group by col1
order by 2 desc
并且每列都有。理想情况下，如果结果是并排的（你可以联合列吗？）
，那就太好了编辑：
我明白了。花了3.5个小时，但我到了那里。第一次使用存储过程和动态SQL，这是一个很好的学习经验。
---- This stored procedure takes the database name and table name and will run a frequency on each column.
DELIMITER $$
DROP PROCEDURE IF EXISTS Data_Audit$$
CREATE PROCEDURE Data_Audit(db_name varchar(100), tbl_name varchar(100))
BEGIN
-- set up variables
DECLARE col_number int;
DECLARE sql_code varchar(255);
SET col_number = 0;
SET @total_rows = 0;
SET @col_count = 0;
-- Set variable to number of columns. Used for number of loops
SELECT COUNT(*)
into @col_count
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = db_name
AND table_name = tbl_name;
-- Set variable to number of rows
set @row_count_code = concat ('set @row_count = (select count(*) FROM ',tbl_name,')');
PREPARE stmt FROM @row_count_code;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
set @drop_new_table = concat('
drop table if exists ',
db_name,
'.',
tbl_name,
'_frequency;');
PREPARE stmt FROM @drop_new_table;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
-- Create basic table structure
set @create_new_table = concat('
create table ',
db_name,
'.',
tbl_name,
'_frequency',
' (Column_Value varchar(100), Frequency varchar(100),Frequency_percent varchar(50))'
';');
-- select @create_new_table
PREPARE stmt FROM @create_new_table;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
-- Loop through columns
WHILE col_number < @col_count DO
SET col_number = col_number + 1;
-- SET @sql = NULL;
-- set @col_num = col_number;
SELECT column_name
INTO @sql_code
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = db_name
AND table_name = tbl_name
AND ordinal_position = col_number;
-- This is the main query. Inserts each time into the new table
SET @sql = CONCAT('insert into ',
db_name,
'.',
tbl_name,
'_frequency Select ''', upper(@sql_code), ''',''Frequency'',''Frequency_percent'' UNION ALL (SELECT `',
@sql_code,
'` , count(*), concat(truncate((count(*) / ',
@row_count,
') *100,2),''%'') as Frequency FROM ',
tbl_name,
' group by `',
@sql_code,
'` order by 2 desc limit 30) UNION ALL Select '''','''',''''');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END WHILE;
END$$
DELIMITER ;
call Data_Audit('world','country');
答案 0 :(得分：1)
我明白了。花了3.5个小时，但我到了那里。第一次使用存储过程和动态SQL，这是一个很好的学习经验。
---- This stored procedure takes the database name and table name and will run a frequency on each column.
DELIMITER $$
DROP PROCEDURE IF EXISTS Data_Audit$$
CREATE PROCEDURE Data_Audit(db_name varchar(100), tbl_name varchar(100))
BEGIN
-- set up variables
DECLARE col_number int;
DECLARE sql_code varchar(255);
SET col_number = 0;
SET @total_rows = 0;
SET @col_count = 0;
-- Set variable to number of columns. Used for number of loops
SELECT COUNT(*)
into @col_count
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = db_name
AND table_name = tbl_name;
-- Set variable to number of rows
set @row_count_code = concat ('set @row_count = (select count(*) FROM ',tbl_name,')');
PREPARE stmt FROM @row_count_code;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
set @drop_new_table = concat('
drop table if exists ',
db_name,
'.',
tbl_name,
'_frequency;');
PREPARE stmt FROM @drop_new_table;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
-- Create basic table structure
set @create_new_table = concat('
create table ',
db_name,
'.',
tbl_name,
'_frequency',
' (Column_Value varchar(100), Frequency varchar(100),Frequency_percent varchar(50))'
';');
-- select @create_new_table
PREPARE stmt FROM @create_new_table;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
-- Loop through columns
WHILE col_number < @col_count DO
SET col_number = col_number + 1;
-- SET @sql = NULL;
-- set @col_num = col_number;
SELECT column_name
INTO @sql_code
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_schema = db_name
AND table_name = tbl_name
AND ordinal_position = col_number;
-- This is the main query. Inserts each time into the new table
SET @sql = CONCAT('insert into ',
db_name,
'.',
tbl_name,
'_frequency Select ''', upper(@sql_code), ''',''Frequency'',''Frequency_percent'' UNION ALL (SELECT `',
@sql_code,
'` , count(*), concat(truncate((count(*) / ',
@row_count,
') *100,2),''%'') as Frequency FROM ',
tbl_name,
' group by `',
@sql_code,
'` order by 2 desc limit 30) UNION ALL Select '''','''',''''');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END WHILE;
END$$
DELIMITER ;
call Data_Audit('world','country');