数据库表空间信息查询 --查看表空间的名称及大小 www.2cto.com SELECT T.TABLESPACE_NAME, ROUND(SUM(D.BYTES / (1024 * 1024)), 0) TS_SIZE FROM DBA_TABLESPACES T, DBA_DATA_FILES D WHERE T.TABLESPACE_NAME = D.TABLESPACE_NAME GROUPBY T.TABLESPACE_N
数据库表空间信息查询
--查看表空间的名称及大小 www.2cto.com
SELECT T.TABLESPACE_NAME, ROUND(SUM(D.BYTES / (1024 * 1024)), 0) TS_SIZE
FROM DBA_TABLESPACES T, DBA_DATA_FILES D
WHERE T.TABLESPACE_NAME = D.TABLESPACE_NAME
GROUPBY T.TABLESPACE_NAME
--查看表空间物理文件的名称及大小
SELECT TABLESPACE_NAME, FILE_ID, FILE_NAME, ROUND(BYTES / (1024 * 1024), 0) TOTAL_SPACE
FROM DBA_DATA_FILES
ORDERBY TABLESPACE_NAME;
--表空间的未用空间
SELECT TABLESPACE_NAME, SUM(BYTES) / (1024 * 1024) MBYTES
FROM DBA_FREE_SPACE
GROUPBY TABLESPACE_NAME;
--数据库的大小,和空间使用情况
SELECT A.TABLESPACE_NAME, A.BYTES TOTAL, B.BYTES USED, C.BYTES FREE,
(B.BYTES * 100) / A.BYTES "USED %", (C.BYTES * 100) / A.BYTES "FREE %"
FROMSYS.SM$TS_AVAIL A, SYS.SM$TS_USED B, SYS.SM$TS_FREE C
WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME AND A.TABLESPACE_NAME = C.TABLESPACE_NAME
--表空间的文件使用情况
SELECT B.FILE_ID 文件ID, B.TABLESPACE_NAME 表空间, B.FILE_NAME 物理文件名,
B.BYTES 总字节数, (B.BYTES - SUM(NVL(A.BYTES, 0))) 已使用, SUM(NVL(A.BYTES, 0)) 剩余,
SUM(NVL(A.BYTES, 0)) / (B.BYTES) * 100剩余百分比
FROM DBA_FREE_SPACE A, DBA_DATA_FILES B
WHERE A.FILE_ID = B.FILE_ID
GROUPBY B.TABLESPACE_NAME, B.FILE_NAME, B.FILE_ID, B.BYTES
ORDERBY B.TABLESPACE_NAME

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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