SQLSERVER用无中生有的思想来替代游标 昨天在MSDN论坛看到一个帖子,帖子中LZ需要根据某列的值把其他列的值插入到额外列 帖子地址: 建表脚本 : 1 USE tempdb t1 6 ( 7 client VARCHAR ( 10 ) , 8 pay_level INT , 9 pay_lv_1 INT , 10 pay_lv_2 INT , 11 p
SQLSERVER用无中生有的思想来替代游标
昨天在MSDN论坛看到一个帖子,帖子中LZ需要根据某列的值把其他列的值插入到额外列
帖子地址:
建表脚本:
1 USE tempdb t1 6 ( 7 client VARCHAR(10) , 8 pay_level INT , 9 pay_lv_1 INT , 10 pay_lv_2 INT , 11 pay_lv_3 INT , 12 pay_lv_4 INT , 13 pay_lv_5 INT , 14 pay_lv_6 INT , 15 pay_lv_7 INT , 16 pay_lv_8 INT , 17 pay_lv_9 INT , 18 pay_lv_10 INT , 19 pay_lv_11 INT , 20 pay_lv_12 INT , 21 pay_lv_13 INT , 22 pay_lv_14 INT , 23 pay_lv_15 INT , 24 pay_lv_16 INT , 25 pay_lv_17 INT , 26 pay_lv_18 INT , 27 pay_lv_19 INT , 28 pay_lv_20 INT , 29 pay_lv_21 INT , 30 pay_lv_22 INT , 31 pay_lv_23 INT , 32 pay_lv_24 INT , 33 pay_lv_25 INT, 34 ); t1 ( client, pay_level, pay_lv_1, pay_lv_2, pay_lv_3, 43 pay_lv_4, pay_lv_5, pay_lv_6, pay_lv_7, pay_lv_8, 44 pay_lv_9, pay_lv_10, pay_lv_11, pay_lv_12, 45 pay_lv_13, pay_lv_14, pay_lv_15, pay_lv_16, 46 pay_lv_17, pay_lv_18, pay_lv_19, pay_lv_20, 47 pay_lv_21, pay_lv_22, pay_lv_23, pay_lv_24, 48 pay_lv_25 ) ((10)), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND(), ) ) * RAND() t1 68 GO ,

MySQL'sBLOBissuitableforstoringbinarydatawithinarelationaldatabase,whileNoSQLoptionslikeMongoDB,Redis,andCassandraofferflexible,scalablesolutionsforunstructureddata.BLOBissimplerbutcanslowdownperformancewithlargedata;NoSQLprovidesbetterscalabilityand

ToaddauserinMySQL,use:CREATEUSER'username'@'host'IDENTIFIEDBY'password';Here'showtodoitsecurely:1)Choosethehostcarefullytocontrolaccess.2)SetresourcelimitswithoptionslikeMAX_QUERIES_PER_HOUR.3)Usestrong,uniquepasswords.4)EnforceSSL/TLSconnectionswith

ToavoidcommonmistakeswithstringdatatypesinMySQL,understandstringtypenuances,choosetherighttype,andmanageencodingandcollationsettingseffectively.1)UseCHARforfixed-lengthstrings,VARCHARforvariable-length,andTEXT/BLOBforlargerdata.2)Setcorrectcharacters

MySQloffersechar, Varchar, text, Anddenumforstringdata.usecharforfixed-Lengthstrings, VarcharerForvariable-Length, text forlarger text, AndenumforenforcingdataAntegritywithaetofvalues.

Optimizing MySQLBLOB requests can be done through the following strategies: 1. Reduce the frequency of BLOB query, use independent requests or delay loading; 2. Select the appropriate BLOB type (such as TINYBLOB); 3. Separate the BLOB data into separate tables; 4. Compress the BLOB data at the application layer; 5. Index the BLOB metadata. These methods can effectively improve performance by combining monitoring, caching and data sharding in actual applications.

Mastering the method of adding MySQL users is crucial for database administrators and developers because it ensures the security and access control of the database. 1) Create a new user using the CREATEUSER command, 2) Assign permissions through the GRANT command, 3) Use FLUSHPRIVILEGES to ensure permissions take effect, 4) Regularly audit and clean user accounts to maintain performance and security.

ChooseCHARforfixed-lengthdata,VARCHARforvariable-lengthdata,andTEXTforlargetextfields.1)CHARisefficientforconsistent-lengthdatalikecodes.2)VARCHARsuitsvariable-lengthdatalikenames,balancingflexibilityandperformance.3)TEXTisidealforlargetextslikeartic

Best practices for handling string data types and indexes in MySQL include: 1) Selecting the appropriate string type, such as CHAR for fixed length, VARCHAR for variable length, and TEXT for large text; 2) Be cautious in indexing, avoid over-indexing, and create indexes for common queries; 3) Use prefix indexes and full-text indexes to optimize long string searches; 4) Regularly monitor and optimize indexes to keep indexes small and efficient. Through these methods, we can balance read and write performance and improve database efficiency.


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