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Type {storage} | Name | Range | Attributes | Default |
---|---|---|---|---|
Numeric {1 byte} |
TINYINT[(M)] | -128 TO 127 [0 to 255 if UNSIGNED] |
AUTO_INCREMENT UNSIGNED, ZEROFILL, SERIAL DEFAULT VALUE |
NULL [0 if NOT NULL] |
Numeric {2 bytes} |
SMALLINT[(M)] | -32,768 to 32,767 [0 to 65,535] |
AUTO_INCREMENT, UNSIGNED, ZEROFILL, SERIAL DEFAULT VALUE |
NULL [0 if NOT NULL] |
Numeric {3 bytes} |
MEDIUMINT[(M)] | -8,388,608 to 8,388,607 [0 to 16,777,215] |
AUTO_INCREMENT, UNSIGNED, ZEROFILL, SERIAL DEFAULT VALUE |
NULL [0 if NOT NULL] |
Numeric {4 bytes} |
INT[(M)] | -/+2.147E+9 [0 to 4.294E+9] |
AUTO_INCREMENT, UNSIGNED, ZEROFILL, SERIAL DEFAULT VALUE |
NULL [0 if NOT NULL] |
Numeric {8 bytes} |
BIGINT[(M)] | -/+9.223E+18 [0 to 18.45E+18] |
AUTO_INCREMENT, UNSIGNED, ZEROFILL, SERIAL DEFAULT VALUE |
NULL [0 if NOT NULL] |
Numeric {4 or 8} |
FLOAT(p) | p=0-24 --> "FLOAT" p=25-53 --> "DOUBLE" |
UNSIGNED, ZEROFILL | NULL [0 if NOT NULL] |
Numeric {4 bytes} |
FLOAT[(M,D)] | Min=+/-1.175E-38 Max=+/-3.403E+38 |
UNSIGNED, ZEROFILL | NULL [0 if NOT NULL] |
Numeric {8 bytes} |
DOUBLE[(M,D)] | Min=+/-2.225E-308 Max=+/-1.798E+308 |
UNSIGNED, ZEROFILL | NULL [0 if NOT NULL] |
Numeric {M+2} |
DECIMAL[(M,[D])] Stored as string |
Max Range = DOUBLE range Fixed point vs. DOUBLE float |
UNSIGNED, ZEROFILL | NULL [0 if NOT NULL] |
Bit {8 bytes} |
BIT[(M)] | Binary. Display by [add zero or converting with BIN()]. M=1-64 | Prior to 5.03 TINYINT(1) Synonym |
NULL [0 if NOT NULL] |
String {M char's} |
CHAR[(M)] | M=0-255 Characters, FIXED. Right padded with spaces. |
BINARY, CHARACTER SET | NULL ["" if NOT NULL] |
String {M char's1} |
VARCHAR(M) | M=0-65,535 Characters M=0-255 BINARY, CHARACTER SET |
NULL | ["" if NOT NULL] |
String {#char's1} |
TINYTEXT2 | 0-255 Characters | BINARY, CHARACTER SET | NULL ["" if NOT NULL] |
String {#char's1} |
TEXT2 | 0-65,535 Char's | BINARY, CHARACTER SET | NULL ["" if NOT NULL] |
String {#char's1} |
MEDIUMTEXT2 | 0-16,777,215 Char's | BINARY, CHARACTER SET | NULL ["" if NOT NULL] |
String {#char's1} |
LONGTEXT2 | 0-4,294,967,295 Char's | BINARY, CHARACTER SET | NULL ["" if NOT NULL] |
String {M bytes} |
BINARY[(M)] | M=0-255 bytes, FIXED. | Global Only (case sensitive) |
NULL ["" if NOT NULL] |
String {M bytes} |
VARBINARY(M) | 0-65,535 bytes M=0-255 Global Only |
(case sensitive) NULL | ["" if NOT NULL] |
String {#bytes1} |
TINYBLOB | 0-255 bytes | Global Only (case sensitive) |
NULL ["" if NOT NULL] |
String {#bytes1} |
BLOB | 0-65,535 bytes | Global Only (case sensitive) |
NULL ["" if NOT NULL] |
String {#bytes1} |
MEDIUMBLOB | 0-16,777,215 bytes | Global Only (case sensitive) |
NULL ["" if NOT NULL] |
String {#bytes1} |
LONGBLOB | 0-4,294,967,295 bytes | Global Only (case sensitive) |
NULL ["" if NOT NULL] |
String {1-2 bytes} |
ENUM2 ("A1","A2",...) |
Column is exactly 1 of 1-65,535 values | CHARACTER SET | NULL [1st value if NOT NULL] |
String {1-8 bytes} |
SET2 ("A1","A2",...) |
Column is 0 or more values in list of 1-64 members | CHARACTER SET | NULL ["" if NOT NULL] |
Date & Time {3 bytes} |
DATE | "1000-01-01" - "9999-12-31" | Global Only (YYYY-MM-DD) |
NULL ["0000-00-00" if NOT NULL] |
Date & Time {8 bytes} |
DATETIME | "1000-01-01 00:00:00" - "9999-12-31 23:59:59" |
Global Only (YYYY-MM-DD hh:mm:ss) |
NULL ["0000-00-00 00:00:00" if NOT NULL] |
Date & Time {3 bytes} |
TIME | "-838:59:59" - "838:59:59" | Global Only (hh:mm:ss) |
NULL ["00:00:00" if NOT NULL] |
Date & Time {4 bytes} |
TIMESTAMP | 19700101000000 - 2037+ |
Global Only (YYYYMMDDhhmmss) |
Current Date & Time |
Date & Time {1 bytes} |
YEAR | 1900 - 2155 | Global Only (YYYY) |
NULL ["0000" if NOT NULL] |
Notes:

MySQLstringtypesimpactstorageandperformanceasfollows:1)CHARisfixed-length,alwaysusingthesamestoragespace,whichcanbefasterbutlessspace-efficient.2)VARCHARisvariable-length,morespace-efficientbutpotentiallyslower.3)TEXTisforlargetext,storedoutsiderows,

MySQLstringtypesincludeVARCHAR,TEXT,CHAR,ENUM,andSET.1)VARCHARisversatileforvariable-lengthstringsuptoaspecifiedlimit.2)TEXTisidealforlargetextstoragewithoutadefinedlength.3)CHARisfixed-length,suitableforconsistentdatalikecodes.4)ENUMenforcesdatainte

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)

ToaddusersinMySQLeffectivelyandsecurely,followthesesteps:1)UsetheCREATEUSERstatementtoaddanewuser,specifyingthehostandastrongpassword.2)GrantnecessaryprivilegesusingtheGRANTstatement,adheringtotheprincipleofleastprivilege.3)Implementsecuritymeasuresl

ToaddanewuserwithcomplexpermissionsinMySQL,followthesesteps:1)CreatetheuserwithCREATEUSER'newuser'@'localhost'IDENTIFIEDBY'password';.2)Grantreadaccesstoalltablesin'mydatabase'withGRANTSELECTONmydatabase.TO'newuser'@'localhost';.3)Grantwriteaccessto'

The string data types in MySQL include CHAR, VARCHAR, BINARY, VARBINARY, BLOB, and TEXT. The collations determine the comparison and sorting of strings. 1.CHAR is suitable for fixed-length strings, VARCHAR is suitable for variable-length strings. 2.BINARY and VARBINARY are used for binary data, and BLOB and TEXT are used for large object data. 3. Sorting rules such as utf8mb4_unicode_ci ignores upper and lower case and is suitable for user names; utf8mb4_bin is case sensitive and is suitable for fields that require precise comparison.

The best MySQLVARCHAR column length selection should be based on data analysis, consider future growth, evaluate performance impacts, and character set requirements. 1) Analyze the data to determine typical lengths; 2) Reserve future expansion space; 3) Pay attention to the impact of large lengths on performance; 4) Consider the impact of character sets on storage. Through these steps, the efficiency and scalability of the database can be optimized.


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