mysql 存储过程小问题
mysql写的存储过程的一些小问题
DELIMITER $$
USE `yzhoteldb`$$
DROP PROCEDURE IF EXISTS `yz_waveData`$$
CREATE DEFINER=`cacdba`@`%` PROCEDURE `yz_waveData`(
IN devCode VARCHAR(32),
IN WhereCondition VARCHAR(100)
)
BEGIN
DECLARE ftime VARCHAR(32);
DECLARE fvalue FLOAT;
-- 参与计算的变量需要写一个默值,否则值一直会变成null
DECLARE sumValue FLOAT DEFAULT 0;
DECLARE avgvalue FLOAT;
DECLARE sqlstr VARCHAR(32767);
DECLARE i INT DEFAULT 0;
DECLARE done INTEGER DEFAULT 0;
DECLARE cur CURSOR FOR SELECT f_time,f_value FROM this_yc201508;
-- 这一句一定要写无数据时done标志为1,否则会无循环的。
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done=1;
CREATE TEMPORARY TABLE IF NOT EXISTS avgDATA
(
F_TIME VARCHAR(32),
F_VALUE FLOAT
);
TRUNCATE avgDATA;
OPEN cur;
FETCH cur INTO ftime,fvalue;
WHILE (done<>1)
DO
SET i=i+1;
SET sumValue=sumValue+fvalue;
SET avgvalue=sumValue/i;
INSERT INTO avgDATA(F_TIME,F_VALUE) VALUES(ftime,avgvalue);
FETCH cur INTO ftime,fvalue;
END WHILE;
CLOSE cur;
-- INSERT INTO avgDATA(F_TIME,F_VALUE) VALUES('1','11');
SELECT * FROM avgDATA;
/*set sqlstr="SELECT * FROM avgDATA ";
select sqlstr;
IF sqlstr<>"" THEN
begin
SET @sqlCommand=sqlstr; 动态语句采用这种形式来写
PREPARE STMT FROM @sqlCommand;
EXECUTE STMT;
DEALLOCATE PREPARE STMT;
end;
END IF; */
END$$
DELIMITER ; -- 没有这一句的话,mysql会把这段SQL当SQL语句而不是存储过程
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