从我的SQL表中导出CSV文件中的数据之前如何检查行数

Question

this below query is working fine for me to export the data from table to csv file but i want handle like if query returns no record then in 'filename.csv' file should contain 'no data found' message for users

-- file name as timestamp
SET @fileName = DATE_FORMAT(NOW(),'%Y-%m-%d-%H:%i:%s');
SET @FOLDER = '/tmp/';
SET @EXT    = '.csv';

SET @CMD = CONCAT("SELECT id,name,salary,salaryDate FROM emp1 where name ='some_name' INTO OUTFILE '"
            ,@FOLDER,@fileName,@EXT,
            "' FIELDS ENCLOSED BY '\"' TERMINATED BY ',' ESCAPED BY '\"'",
            "  LINES TERMINATED BY '\n';"); 
PREPARE statement FROM @CMD;
EXECUTE statement;

where do i need to change ? Any one can help me ?

Answer 1

You should create stored procedure. Check row numbers using COUNT function, then output one of results you need, for example -

CREATE PROCEDURE procedure1()
BEGIN
  IF (SELECT COUNT(*) FROM emp1 where name ='some_name') = 0 THEN 
    SELECT 'no data found' INTO OUTFILE 'file_name.csv';
  ELSE
    your code here - SELECT INTO OUTFILE
  END IF;
END