基礎(chǔ)3sql server數(shù)據(jù)庫5 Sql語句簡單理解就是用于操作的

Dns解析系Ip地址\MysqlSqlSQLSql o’’World!’ 數(shù)據(jù)庫對象(表名,庫中名,列名可以用[]括起來,1)防止和關(guān)鍵字2)對象名之間有空DroptableDropdatabase要刪除的數(shù)據(jù)庫名修改表語法:altertable表名……修改表結(jié)構(gòu)時,一定要注意會不會原來表中的數(shù)據(jù)有--altertable表名dropcolumn要刪除的列名;altertabletblStudentdropcolumntSCla --altertable表名addaltertabletblStudentadd --altertable表名altercolumnaltertabletblStudentaltercolumn intnot--altertable表名addconstraint主鍵約束名primarykey(主鍵列)altertableTblStudentaddconstraintPK_TblStudent_tSIdPrimaryaltertabletblStudentdropconstraint對數(shù)據(jù)庫,最常用的就是增 刪 改 查查:語法 Select*from表 顯示表中的所有數(shù)useselect*fromStudent--select后的*,SELECTstuId,stuAddress,'我也不知道asnewColfromselectstuName,stuAddress,stuName+stuAddressas'+地址'fromselecttestId+stuIdfromSELECTstuIdas學(xué)號],stuName,stuAddressfromSELECTstuIdas[學(xué)號],stuName,stuAddressfromSELECTstuIdas[學(xué)號],stuName,'地址'=stuAddressfrom--要求：兩個結(jié)果集的列數(shù)必須相同2兩個結(jié)果集對應(yīng)列的數(shù)據(jù)類型相同select*fromScoreselectstuId,testBasetestName,testDatefromscorewherestuId=1union--合并結(jié)果集selectstuId,testBase,testName,testDatefromscorewhereselectcol1from selectCol2as'aaa'fromtblTest2--語法:insertinto表名(列名，列名 insertintoTblClass(tClassName,tClassDesc)insertintoTblClass(tClassName) select*from--insertintoTblClass(tClassDescvalues('這里是描述insertintoTblClassvalues('未命名班','還沒想好班名--SETIDENTITY_INSERT表名setidentity_inserttblclassinsertintoTblClass(tCla setidentity_inserttblclassOff不允許手動設(shè)置自動增漲列了insertintoTblClass(tClassName,tClassDesc)select*fromTblClass--語法：insertinto表名[(列名,列 insertintoTblClass(tClassName,tClassDesc)select'','我喜歡的地方'unionselect'班','明天開unionselect'','都是'unionselect'楊','班'insertintoselecttSAddress,tSPhonefromTblStudentselect*fromTblClassinsertintoselecttSGender,tSAddress,tSPhone,tSAge,tSBirthday,tSCardId,tSCla fromTblStudentselect*fromTblStudent--select*from表名在列名后加上into新表名注意：新表必須不存在select*intonewClassAfromTblClassselecttClassName,tClassDescintonewClassColsfromTblClassselect*fromnewClasscolsselect*fromselecttClassName,tClassDescintonewClassWherefromTblClasswheretCla select*fromupdate表名set要更新的列名=新值[,要更新的列名=新值[where表達(dá)式]useTestDataBaseselect*intonewStudentfromStudentselect*fromnewStudentupdatenewStudentset updatenewStudentsetstuIsDel=1,cla select*fromnewStudentupdaTEnewStudentset select*fromupdateScoresettestBase=testBase-1select*fromscoreselect*fromScorewhereupdateScoresettestBase=testBase+5wherestuId=1select*fromScorewherestuId=1delete--刪除的語法deletefrom表名select*fromnewStudentdeletefromnewStudentselect*fromselect*fromnewStudentwherecla =1andstu deletefromnewStudentwherecla =1andstu --語法truncatetableselect*fromnewStudenttruncatetable約束是保證數(shù)據(jù)庫完數(shù)據(jù)為完整性說白了就是保證數(shù)據(jù)庫中的比如:,只有男和女 唯一約束:select*frominsertintoTblClassvalues('期','12-28')deletefromTblClasswheretCla --語法altertable表名addconstraint約束名約束的關(guān)鍵字(列名)...altertabletblclassaddconstraintUQ_tblClass_tClassDescUnique(tClassDesc)select*fromTblClassinsertintoTblClass(tClassDesc)values('ttt12-28altertabletblClassaddconstraintDF_TblClass_tClassDescDefault(N'')fortClassDescinsertintoTblClass(tClassName)values('測試就業(yè)班')updateTblClasssettclassmaxstudent=50select*fromTblClassinsertintoTblClassvalues('11',' selectLEN(tclassName),tclassNamefromTblClassaltertabletblClassaddconstraintCK_