当前week的第一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 1 DAY)
当前week的最后一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) – 5 DAY)
前一week的第一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 8 DAY)
前一week的最后一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 2 DAY)
前两week的第一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 15 DAY)
前两week的最后一天:
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 9 DAY)
当前month的第一天:
SELECT concat(date_format(LAST_DAY(now()),’%Y-%m-’),’01′)
当前month的最后一天:
SELECT LAST_DAY(now())
前一month的第一天:
SELECT concat(date_format(LAST_DAY(now() – interval 1 month),’%Y-%m-’),’01′)
前一month的最后一天:
SELECT LAST_DAY(now() – interval 1 month)
前两month的第一天:
SELECT concat(date_format(LAST_DAY(now() – interval 2 month),’%Y-%m-’),’01′)
前两month的最后一天:
SELECT LAST_DAY(now() – interval 2 month)
当前quarter的第一天:
select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-3 month),’%Y-%m-’),’01′)
当前quarter的最后一天:
select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-1 month)
前一quarter的第一天:
select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-6 month),’%Y-%m-’),’01′)
前一quarter的最后一天:
select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-4 month)
前两quarter的第一天:
select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-9 month),’%Y-%m-’),’01′)
前两quarter的最后一天:
select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-7 month)

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.

ToaddauserremotelytoMySQL,followthesesteps:1)ConnecttoMySQLasroot,2)Createanewuserwithremoteaccess,3)Grantnecessaryprivileges,and4)Flushprivileges.BecautiousofsecurityrisksbylimitingprivilegesandaccesstospecificIPs,ensuringstrongpasswords,andmonitori

TostorestringsefficientlyinMySQL,choosetherightdatatypebasedonyourneeds:1)UseCHARforfixed-lengthstringslikecountrycodes.2)UseVARCHARforvariable-lengthstringslikenames.3)UseTEXTforlong-formtextcontent.4)UseBLOBforbinarydatalikeimages.Considerstorageov

When selecting MySQL's BLOB and TEXT data types, BLOB is suitable for storing binary data, and TEXT is suitable for storing text data. 1) BLOB is suitable for binary data such as pictures and audio, 2) TEXT is suitable for text data such as articles and comments. When choosing, data properties and performance optimization must be considered.

No,youshouldnotusetherootuserinMySQLforyourproduct.Instead,createspecificuserswithlimitedprivilegestoenhancesecurityandperformance:1)Createanewuserwithastrongpassword,2)Grantonlynecessarypermissionstothisuser,3)Regularlyreviewandupdateuserpermissions

MySQLstringdatatypesshouldbechosenbasedondatacharacteristicsandusecases:1)UseCHARforfixed-lengthstringslikecountrycodes.2)UseVARCHARforvariable-lengthstringslikenames.3)UseBINARYorVARBINARYforbinarydatalikecryptographickeys.4)UseBLOBorTEXTforlargeuns


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