加密解密UTF8编码的BASE64串 无 GOCREATE FUNCTION [dbo].[c_GetUTF8Code] ( @char Nchar )RETURNS intAS--UTF8转码BEGIN Declare @Code int Select @Code=Cast(Unicode(@char) as int) Declare @Utf8Code int Set @Utf8Code=0 if(@Code128) begin --0-127 --
加密解密UTF8编码的BASE64串
GO CREATE FUNCTION [dbo].[c_GetUTF8Code] ( @char Nchar ) RETURNS int AS --UTF8转码 BEGIN Declare @Code int Select @Code=Cast(Unicode(@char) as int) Declare @Utf8Code int Set @Utf8Code=0 if(@Code<128) begin --0-127 --0000-007F --0xxxxxxx --01100010 Unocide --01100010 UTF-8 Set @Utf8Code=@Code end else if(@Code>127 and @Code<2048) begin --128-2047 --0080-07FF --110xxx xx10xx xxxx --110 7 F F Declare @C1 int Declare @C2 int Declare @C3 int Select @C1=@Code/0x100 Select @C2=(@Code%0x100)/0x10 Select @C3=@Code%0x10 Select @Utf8Code=0xC080+0x400*@C1+0x100*(@C2/4)+0x10*(@C2%4)+@C3 end else if(@Code>2047 and @Code<65536) begin --2047-65535 --0110 0010 0001 0001 --1110 xxxx 10xx xxxx 10xx xxxx --1110 0110 1000 1000 1001 0001 Declare @C11 int Declare @C12 int Declare @C13 int Declare @C14 int Select @C11=@Code/0x1000 Select @C12=(@Code%0x1000)/0x100 Select @C13=(@Code%0x100)/0x10 Select @C14=@Code%0x10 Select @Utf8Code=0xE08080+0x10000*@C11+0x400*@C12+0x100*(@C13/4)+0x10*(@C13%4)+@C14 end return @Utf8Code End GO CREATE FUNCTION [dbo].[base64_utf8encode] ( @plain_text varchar(max) ) RETURNS varchar(max) AS BEGIN --Base64解密 DECLARE @output varchar(max) DECLARE @block_start integer DECLARE @map char(64) SET @map='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' SET @output='' SET @block_start=0 Declare @plain_textLength int Set @plain_textLength=Len(@plain_text) Declare @RestTransfer int--转码数累积 Declare @RestTransferLenth int Set @RestTransfer=0 Set @RestTransferLenth=0 Declare @CodeInt int Declare @block_val BINARY(3) WHILE @block_start<@plain_textLength BEGIN Set @CodeInt=0 SELECT @CodeInt= [dbo].[c_GetUTF8Code](SubString(@plain_text,@block_start+1,1)) Declare @CodeTransfer int Set @CodeTransfer=0 --0-127 1位 --128-2047 2位 --2047-65535 3位 if(@CodeInt<128) begin --+1位 if(@RestTransferLenth=0 or @RestTransferLenth=1) begin Set @RestTransfer=@RestTransfer*0x100+@CodeInt Set @RestTransferLenth=@RestTransferLenth+1 end else if(@RestTransferLenth=2) begin Set @CodeTransfer=@RestTransfer*0x100+@CodeInt Set @RestTransfer=0 Set @RestTransferLenth=0 end end else if(@CodeInt>127 and @CodeInt<2048) begin --+2位 if(@RestTransferLenth=0) begin Set @RestTransfer=@CodeInt Set @RestTransferLenth=2 end else if(@RestTransferLenth=1) begin Set @CodeTransfer=0x10000*@RestTransfer+@CodeInt Set @RestTransfer=0 Set @RestTransferLenth=0 end else if(@RestTransferLenth=2) begin Set @CodeTransfer=0x100*@RestTransfer+@CodeInt/0x100 Set @RestTransfer=@CodeInt%0x100 Set @RestTransferLenth=1 end end else if(@CodeInt>2047) begin --+3位 if(@RestTransferLenth=0) begin Set @CodeTransfer=@CodeInt Set @RestTransfer=0 Set @RestTransferLenth=0 end else if(@RestTransferLenth=1) begin Set @CodeTransfer=0x10000*@RestTransfer+@CodeInt/0x100 Set @RestTransfer=@CodeInt%0x100 Set @RestTransferLenth=1 end else if(@RestTransferLenth=2) begin --剩余部分十六进制右移两位与新数据前两位之和 Set @CodeTransfer=0x100*@RestTransfer+@CodeInt/0x10000 Set @RestTransfer=@CodeInt%0x10000 Set @RestTransferLenth=2 end end ---累积到3位,执行加密转换 if(@CodeTransfer>0x100000) begin SET @block_val = CAST(@CodeTransfer AS BINARY(3)) SET @output = @output + SUBSTRING(@map , @block_val/262144 +1,1) + SUBSTRING(@map ,(@block_val/4096&63)+1,1) + SUBSTRING(@map ,(@block_val/64 &63)+1,1) + SUBSTRING(@map ,(@block_val&63) +1,1) end SET @block_start=@block_start+1 END IF @RestTransferLenth>0 BEGIN SET @block_val=Cast(@RestTransfer*(Case @RestTransferLenth When 1 Then 65536 Else 256 end) as BINARY(3)) SET @output=@output +SUBSTRING(@map , @block_val/262144+1, 1) +SUBSTRING(@map ,(@block_val/4096 &63)+1,1) +CASE WHEN @RestTransferLenth =1 THEN REPLACE(SUBSTRING(@map ,(@block_val/64&63)+1,1),'A','=') ELSE SUBSTRING(@map ,(@block_val/64&63)+1,1) END +CASE WHEN @RestTransferLenth=1 THEN '=' ELSE REPLACE(SUBSTRING(@map ,(@block_val&63)+1,1),'A','=') END END RETURN @output END GO CREATE FUNCTION [dbo].[base64_utf8decode] ( @encoded_text varchar(max) ) RETURNS varchar(max) AS BEGIN --BASE64加密 DECLARE @output varchar(max) DECLARE @block_start int DECLARE @encoded_length int DECLARE @decoded_length int DECLARE @mapr binary(122) SET @output = '' SET @mapr = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF -- 1-33 +0xFFFFFFFFFFFFFFFFFFFF3EFFFFFF3F3435363738393A3B3C3DFFFFFF00FFFFFF -- 33-64 +0x000102030405060708090A0B0C0D0E0F10111213141516171819FFFFFFFFFFFF -- 65-96 +0x1A1B1C1D1E1F202122232425262728292A2B2C2D2E2F30313233-- 97-122 SET @encoded_length=LEN(@encoded_text) SET @decoded_length=@encoded_length/4*3 SET @block_start=1 Declare @Code int Set @Code=0 Declare @CodeLength int--累计连接数,1,2,3 Set @CodeLength =0 WHILE @block_start<@encoded_length BEGIN Declare @Integer Integer Set @Integer=substring(@mapr,Unicode(substring(@encoded_text,@block_start ,1)),1)*262144 + substring(@mapr,Unicode(substring(@encoded_text,@block_start+1,1)),1)*4096 + substring(@mapr,Unicode(substring(@encoded_text,@block_start+2,1)),1)*64 + substring(@mapr,Unicode(substring(@encoded_text,@block_start+3,1)),1) Declare @C1 int Declare @C2 int Declare @C3 int --0xFF FF FF Set @C1=@Integer/0x10000 Set @C2=(@Integer/0x100)%0x100 Set @C3=@Integer%0x100 -------------------------------------@C1 if(@C1<0x80) begin if(@CodeLength=2) begin --128-2047 --0080-07FF --110x xx xx 10xx xxxx Set @Code=((@Code%0x2000)/0x100)*0x10+@Code%0x40 SET @output=@output+NCHAR(@Code) --print @Code Set @Code=0 Set @CodeLength=0 end SET @output=@output+CAST(Cast(@C1 AS BINARY(1))AS VARCHAR(1)) end else begin --码字连接 Set @Code=@Code*0x100+@C1 SET @CodeLength=@CodeLength+1 if(@CodeLength=3) begin --0110 0010 0001 0001 --1110 xxxx 10xx xxxx 10xx xxxx --1110 0110 1000 1000 1001 0001 Set @Code=((@Code%0x100000)/0x10000)*0x1000+((@Code%0x4000)/0x100)*0x40+@Code%0x40 SET @output=@output+NCHAR(@Code) Set @Code=0 Set @CodeLength=0 end end -------------------------------------@C2 if(@C2<0x80) begin if(@CodeLength=2) begin --128-2047 --0080-07FF --110x xx xx 10xx xxxx Set @Code=((@Code%0x2000)/0x100)*0x10+@Code%0x40 SET @output=@output+NCHAR(@Code) --print @Code Set @Code=0 Set @CodeLength=0 end SET @output=@output+CAST(Cast(@C2 AS BINARY(1))AS VARCHAR(1)) end else begin --码字连接 Set @Code=@Code*0x100+@C2 SET @CodeLength=@CodeLength+1 if(@CodeLength=3) begin --0110 0010 0001 0001 --1110 xxxx 10xx xxxx 10xx xxxx --1110 0110 1000 1000 1001 0001 Set @Code=((@Code%0x100000)/0x10000)*0x1000+((@Code%0x4000)/0x100)*0x40+@Code%0x40 SET @output=@output+NCHAR(@Code) Set @Code=0 Set @CodeLength=0 end end -------------------------------------@C3 if(@C3<0x80) begin if(@CodeLength=2) begin --128-2047 --0080-07FF --110x xx xx 10xx xxxx Set @Code=((@Code%0x2000)/0x100)*0x10+@Code%0x40 SET @output=@output+NCHAR(@Code) --print @Code Set @Code=0 Set @CodeLength=0 end SET @output=@output+CAST(Cast(@C3 AS BINARY(1))AS VARCHAR(1)) end else begin --码字连接 Set @Code=@Code*0x100+@C3 SET @CodeLength=@CodeLength+1 if(@CodeLength=3) begin --0110 0010 0001 0001 --1110 xxxx 10xx xxxx 10xx xxxx --1110 0110 1000 1000 1001 0001 Set @Code=((@Code%0x100000)/0x10000)*0x1000+((@Code%0x4000)/0x100)*0x40+@Code%0x40 SET @output=@output+NCHAR(@Code) Set @Code=0 Set @CodeLength=0 end end SET @block_start = @block_start + 4 END IF RIGHT(@encoded_text,2)='==' SET @decoded_length=@decoded_length-2 ELSE IF RIGHT(@encoded_text,1)='=' SET @decoded_length=@decoded_length-1 RETURN LEFT(@output ,@decoded_length) END

mySqlStringTypesimpactStorageAndPerformanCeaseAsfollows:1)長度,始終使用theSamestoragespace,whatcanbefasterbutlessspace-felfficity.2)varCharisvariable varcharisvariable length,morespace-morespace-morespace-effficitybuteftife buteftife butfority butfority textifforlyslower.3)

mysqlStringTypesIncludeVarChar,文本,char,Enum和set.1)varCharisVersAtileForvariable-lengthStringStringSuptoPuptOuptoPepePecifiedLimit.2)textisidealforlargetStortStorStoverStoverStorageWithoutAutAdefinedLength.3)charlisfixed-lenftenge,for forConsistentDatalikeCodes.4)

MySQLoffersvariousstringdatatypes:1)CHARforfixed-lengthstrings,2)VARCHARforvariable-lengthtext,3)BINARYandVARBINARYforbinarydata,4)BLOBandTEXTforlargedata,and5)ENUMandSETforcontrolledinput.Eachtypehasspecificusesandperformancecharacteristics,sochoose

TograntpermissionstonewMySQLusers,followthesesteps:1)AccessMySQLasauserwithsufficientprivileges,2)CreateanewuserwiththeCREATEUSERcommand,3)UsetheGRANTcommandtospecifypermissionslikeSELECT,INSERT,UPDATE,orALLPRIVILEGESonspecificdatabasesortables,and4)

toadduserInmysqleffect和securly,跟隨台詞:1)USEtheCreateUserStattoDaneWuser,指定thehostandastrongpassword.2)GrantNecterAryAryaryPrivilegesSustherthing privilegesgeStatement,usifementStatement,adheringtotheprinciplelastprefilegege.3)

toaddanewuserwithcomplexpermissionsinmysql,loldtheSesteps:1)創建eTheEserWithCreateuser'newuser'newuser'@''localhost'Indedify'pa ssword';。 2)GrantreadAccesstoalltablesin'mydatabase'withGrantSelectOnMyDatabase.to'newuser'@'localhost';。 3)GrantWriteAccessto'

MySQL中的字符串數據類型包括CHAR、VARCHAR、BINARY、VARBINARY、BLOB、TEXT,排序規則(Collations)決定了字符串的比較和排序方式。 1.CHAR適合固定長度字符串,VARCHAR適合可變長度字符串。 2.BINARY和VARBINARY用於二進制數據,BLOB和TEXT用於大對像數據。 3.排序規則如utf8mb4_unicode_ci忽略大小寫,適合用戶名;utf8mb4_bin區分大小寫,適合需要精確比較的字段。

最佳的MySQLVARCHAR列長度選擇應基於數據分析、考慮未來增長、評估性能影響及字符集需求。 1)分析數據以確定典型長度;2)預留未來擴展空間;3)注意大長度對性能的影響;4)考慮字符集對存儲的影響。通過這些步驟,可以優化數據庫的效率和擴展性。


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