實訓(xùn)案例名稱：游標(biāo)一、任務(wù)介紹游標(biāo)是一個存儲在MySQL數(shù)據(jù)庫里用來查詢的對象，它可以每次從結(jié)果集里獲取一行數(shù)據(jù)，進行相應(yīng)的處理。有了游標(biāo)，就可以滾動查詢滿足條件的數(shù)據(jù)，可以做一些復(fù)雜的處理。二、實現(xiàn)步驟1.使用游標(biāo)#使用用戶名root和相應(yīng)密碼，連接本地MySQLC:\Users\Administrator>mysql-uroot-p123456mysql:[Warning]Usingapasswordonthecommandlineinterfacecanbeinsecure.#使用shop數(shù)據(jù)庫mysql>USEshopDatabasechanged#創(chuàng)建員工表employee_infomysql>CREATETABLEemployee_info(idintnotnullAUTO_INCREMENT,namevarchar(255),salaryint,primarykey(id));QueryOK,0rowsaffected(0.36sec)#向員工表employee_info插入數(shù)據(jù)mysql>INSERTINTOemployee_infoVALUES(1,'小明',3700),(2,'小紅',5700),(3,'小藍',7800);QueryOK,3rowsaffected(0.01sec)Records:3Duplicates:0Warnings:0#查詢員工表employee_info的數(shù)據(jù)，使用SELECT語句，一次獲取滿足條件的所有數(shù)據(jù)mysql>SELECT*FROMemployee_info;+----+------+--------+|id|name|salary|+----+------+--------+|1|小明|3700||2|小紅|5700||3|小藍|7800|+----+------+--------+3rowsinset(0.01sec)#修改結(jié)束符$$mysql>DELIMITER$$#創(chuàng)建存儲過程p2()，定義游標(biāo)cursor2，讀取每一行數(shù)據(jù)mysql>CREATEPROCEDUREp2()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREcursor2CURSORFORSELECTid,name,salaryFROMemployee_info;OPENcursor2;FETCHcursor2INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;FETCHcursor2INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;FETCHcursor2INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;CLOSEcursor2;END$$QueryOK,0rowsaffected(0.00sec)#修改結(jié)束符mysql>DELIMITER;#調(diào)用存儲過程p2()mysql>CALLp2();#使用游標(biāo)一次，輸出一次結(jié)果+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|1|小明 | 3700|+------+--------+----------+1rowinset(0.00sec)#使用游標(biāo)一次，輸出一次結(jié)果+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|2|小紅 | 5700|+------+--------+----------+1rowinset(0.01sec)#使用游標(biāo)一次，輸出一次結(jié)果+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|3|小藍|7800|+------+--------+----------+1rowinset(0.02sec)mysql>2.游標(biāo)的WHILE循環(huán)#使用用戶名root和相應(yīng)密碼，連接本地MySQLC:\Users\Administrator>mysql-uroot-p123456mysql:[Warning]Usingapasswordonthecommandlineinterfacecanbeinsecure.#使用shop數(shù)據(jù)庫mysql>USEshopDatabasechanged#查詢員工表employee_infomysql>SELECT*FROMemployee_info;+----+------+--------+|id|name|salary|+----+------+--------+|1|小明|3700||2|小紅|5700||3|小藍|7800|+----+------+--------+3rowsinset(0.00sec)#修改結(jié)束符$$mysql>DELIMITER$$#定義一個存儲過程，先計算出結(jié)果總條數(shù)，再使用WHILE循環(huán)mysql>CREATEPROCEDUREp3()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREsumintdefault0;DECLAREcursor3CURSORFORSELECTid,name,salaryFROMemployee_info;SELECTcount(*)INTOsumFROMemployee_info;OPENcursor3;WHILE(sum>0)DOFETCHcursor3INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary,sum;SETsum=sum-1;ENDWHILE;CLOSEcursor3;END$$#修改結(jié)束符mysql>DELIMITER;#調(diào)用存儲過程，輸出每次循環(huán)的結(jié)果mysql>CALLp3();+------+--------+----------+------+|c_id|c_name|c_salary|sum|+------+--------+----------+------+|1|小明|3700|3|+------+--------+----------+------+1rowinset(0.01sec)+------+--------+----------+------+|c_id|c_name|c_salary|sum|+------+--------+----------+------+|2|小紅|5700|2|+------+--------+----------+------+1rowinset(0.02sec)+------+--------+----------+------+|c_id|c_name|c_salary|sum|+------+--------+----------+------+|3|小藍|7800|1|+------+--------+----------+------+1rowinset(0.02sec)QueryOK,0rowsaffected(0.04sec)#刪除存儲過程mysql>DROPPROCEDUREp3;#修改結(jié)束符$$mysql>DELIMITER$$#mysql>CREATEPROCEDUREp3()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREflagintdefault0;DECLAREcursor3CURSORFORSELECTid,name,salaryFROMemployee_info;DECLARECONTINUEHANDLERFORNOTFOUNDSETflag=1;OPENcursor3;WHILE(flag=0)DOFETCHcursor3INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;ENDWHILE;CLOSEcursor3;END$$#修改結(jié)束符mysql>DELIMITER;/*設(shè)置為1時，存儲過程會調(diào)用CONTINUE命令繼續(xù)查詢一次，但是調(diào)用EXIT命令時不會繼續(xù)查詢*/mysql>CALLp3();+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|1|小明|3700|+------+--------+----------+1rowinset(0.00sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|2|小紅|5700|+------+--------+----------+1rowinset(0.01sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|3|小藍|7800|+------+--------+----------+1rowinset(0.01sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|3|小藍|7800|+------+--------+----------+1rowinset(0.02sec)QueryOK,0rowsaffected(0.03sec)#刪除存儲過程mysql>DROPPROCEDUREp3;#修改結(jié)束符$$mysql>DELIMITER$$#使用EXIT進行變量判斷，如果找不到，則設(shè)置變量值為1mysql>CREATEPROCEDUREp3()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREflagintdefault0;DECLAREcursor3CURSORFORSELECTid,name,salaryFROMemployee_info;DECLAREEXITHANDLERFORNOTFOUNDSETflag=1;OPENcursor3;WHILE(flag=0)DOFETCHcursor3INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;ENDWHILE;CLOSEcursor3;END$$QueryOK,0rowsaffected(0.00sec)#修改結(jié)束符mysql>DELIMITER;#調(diào)用存儲過程mysql>CALLp3();+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|1|小明|3700|+------+--------+----------+1rowinset(0.00sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|2|小紅|5700|+------+--------+----------+1rowinset(0.01sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|3|小藍|7800|+------+--------+----------+1rowinset(0.02sec)QueryOK,0rowsaffected(0.03sec)mysql>3.游標(biāo)的REPEAT循環(huán)#使用用戶名root和相應(yīng)密碼，連接本地MySQLC:\Users\Administrator>mysql-uroot-p123456mysql:[Warning]Usingapasswordonthecommandlineinterfacecanbeinsecure.#使用shop數(shù)據(jù)庫mysql>USEshopDatabasechanged#查詢員工表employee_infomysql>SELECT*FROMemployee_info;+----+--------+--------+|id|name|salary|+----+--------+--------+|1|小明|3700||2|小紅|5700||3|小藍|7800|+----+--------+--------+3rowsinset(0.00sec)#修改結(jié)束符$$mysql>DELIMITER$$#定義存儲過程p4()，定義游標(biāo)cursor4，使用REPEAT循環(huán)mysql>CREATEPROCEDUREp4()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREflagintdefault0;DECLAREcursor4CURSORFORSELECTid,name,salaryFROMemployee_info;DECLAREEXITHANDLERFORNOTFOUNDSETflag=1;OPENcursor4;REPEATFETCHcursor4INTOc_id,c_name,c_salary;SELECTc_id,c_name,c_salary;UNTILflag=1ENDREPEAT;CLOSEcursor4;END$$QueryOK,0rowsaffected(0.00sec)#修改結(jié)束符mysql>DELIMITER;#調(diào)用存儲過程p4()，循環(huán)輸出結(jié)果mysql>CALLp4();+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|1|小明|3700|+------+--------+----------+1rowinset(0.00sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|2|小紅|5700|+------+--------+----------+1rowinset(0.01sec)+------+--------+----------+|c_id|c_name|c_salary|+------+--------+----------+|3|小藍|7800|+------+--------+----------+1rowinset(0.04sec)QueryOK,0rowsaffected(0.05sec)mysql>4.游標(biāo)的LOOP循環(huán)#使用用戶名root和相應(yīng)密碼，連接本地MySQLC:\Users\Administrator>mysql-uroot-p123456mysql:[Warning]Usingapasswordonthecommandlineinterfacecanbeinsecure.#使用shop數(shù)據(jù)庫mysql>USEshopDatabasechanged#查看員工表employee_info的數(shù)據(jù)mysql>SELECT*FROMemployee_info;+----+--------+--------+|id|name|salary|+----+--------+--------+|1|小明|3700||2|小紅|5700||3|小藍|7800|+----+--------+--------+3rowsinset(0.00sec)#修改結(jié)束符$$mysql>DELIMITER$$#創(chuàng)建存儲過程p5()，定義游標(biāo)cursor5，使用LOOP循環(huán)mysql>CREATEPROCEDUREp5()BEGINDECLAREc_idint;DECLAREc_namevarchar(20);DECLAREc_salaryint;DECLAREflagintdefault0;DECLAREcursor5CURSORFORSELECTid,name,salaryFROMemployee_info;DECLAREEXITHANDLERFORNOT