TINYINT -128 127 TINYINT UNSIGNED 0 255 SMALLINT -32768 32767 SMALLINT UNSIGNED 0 65535 MEDIUMINT -8388608 8388607 MEDIUMINT UNSIGNED 0 16777215 INT 或 INTEGER -2147483648 2147483647 INT UNSIGNED 或 INTEGER UNSIGNED 0 4294967295 BIGINT -92
TINYINT
-128 – 127
TINYINT UNSIGNED
0 – 255
SMALLINT
-32768 – 32767
SMALLINT UNSIGNED
0 – 65535
MEDIUMINT
-8388608 – 8388607
MEDIUMINT UNSIGNED
0 – 16777215
INT 或 INTEGER
-2147483648 – 2147483647
INT UNSIGNED 或 INTEGER UNSIGNED
0 – 4294967295
BIGINT
-9223372036854775808 – 9223372036854775807
BIGINT UNSIGNED
0 – 18446744073709551615
FLOAT
-3.402823466E+38 – -1.175494351E-38
0
1.175494351E-38 – 3.402823466E+38
DOUBLE 或 DOUBLE PRECISION 或 REAL
-1.7976931348623157E+308 – -2.2250738585072014E-308
0
2.2250738585072014E-308 – 1.7976931348623157E+308
DECIMAL[(M,[D])] 或 NUMERIC(M,D)
由M(整个数字的长度,包括小数点,小数点左边的位数,小数点右边的位数,但不包括负号)和D(小数点右边的位数)来决定,M缺省为10,D缺省为0
DATE
1000-01-01 – 9999-12-31
DATETIME
1000-01-01 00:00:00 – 9999-12-31 23:59:59
TIMESTAMP
1970-01-01 00:00:00 – 2037年的某天(具体是哪天我也不知道,呵呵)
TIME
-838:59:59′ to 838:59:59
YEAR[(2|4)]
缺省为4位格式,4位格式取值范围为1901 – 2155,0000,2位格式取值范围为70-69(1970-2069)
CHAR(M) [BINARY] 或 NCHAR(M) [BINARY]
M的范围为1 – 255,如果没有BINARY项,则不分大小写,NCHAR表示使用缺省的字符集.在数据库中以空格补足,但在取出来时末尾的空格将自动去掉.
[NATIONAL] VARCHAR(M) [BINARY]
M的范围为1 – 255.在数据库中末尾的空格将自动去掉.
TINYBLOB 或 TINYTEXT
255(2^8-1)个字符
BLOB 或 TEXT
65535(2^16-1)个字符
MEDIUMBLOB 或 MEDIUMTEXT
16777215 (2^24-1)个字符
LONGBLOB 或 LONGTEXT
4294967295 (2^32-1)个字符
ENUM(‘value1′,’value2′,…)
可以总共有65535个不同的值
SET(‘value1′,’value2′,…)
最多有64个成员
,
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Adding MySQL users through the PHP web interface can use MySQLi extensions. The steps are as follows: 1. Connect to the MySQL database and use the MySQLi extension. 2. Create a user, use the CREATEUSER statement, and use the PASSWORD() function to encrypt the password. 3. Prevent SQL injection and use the mysqli_real_escape_string() function to process user input. 4. Assign permissions to new users and use the GRANT statement.

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

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