使用LENGTH(str:varchar)用于获取存储字符串的字节数(需要注意不是实际存储的字节数,实际存储的字节数需要加上1或2) CHAR和VARCHAR存储字符串方式不同:CHAR存储字符串时如果字符串不足指定长度,那么会在右侧添加剩余长度的空格,当检索或者获取CHAR类型的值时,尾部空格会移除。 VARCHAR使用1字节或者2字节长度前缀,然后...
YEAR:range 1901 to 2155, or 0000 注意:YEAR(4) and YEAR(2)不同之处在于显示不同;eg:70 (1970 or 2070) or 69 (2069). 字符串 CHAR:0 to 255 定长,存储时用空格补齐;读取时删掉后面的空格,PAD_CHAR_TO_FULL_LENGTH sql模式开启 VARCHAR:0 to 65,535 可变长度 BLOB:保存二进制的大型数据(字节串...
col_name{CHAR|VARCHAR|TEXT} (col_length)[CHARACTER SET charset_name][COLLATE collation_name] MySQL chooses the column character set and collation in the following manner: • If both CHARACTER SET charset_name and COLLATE collation_name are specified, character set charset_name and collation coll...
VARCHAR(M)占用存储空间是1+Mn或者2+Mn其中Mn是字符串本身所占存储空间大小,以utf8和utf8mb4为例,这两个字符集都是变长字符集,不同字符使用不同存储空间。除了字符串本身所占存储空间还需要加上1到2个字节的存储空间,1还是2取决于字符串本身所占存储空间是小于255个字节还是大于255个字节。使用LENGTH(str:va...
CREATETABLEwords(idINTPRIMARYKEYAUTO_INCREMENT,wordVARCHAR(255)NOTNULL,meaningTEXTNOTNULL); 1. 2. 3. 4. 5. 插入数据 接下来我们可以向words表中插入一些新华字典的数据,例如: INSERTINTOwords(word,meaning)VALUES('学','学习、学问的简称');INSERTINTOwords(word,meaning)VALUES('爱','喜爱、热爱'); ...
Max Index Name Length The maximum number of characters in an index name. Distinct Type Name The default name for the column type indicated by java.sql.Types.DISTINCT. The mapping tool uses the name when it generates a schema. Character Column Size The default size of VARCHAR and CHAR columns...
col_name {CHAR | VARCHAR | TEXT} (col_length) [CHARACTER SET charset_name [COLLATE collation_name]] Example: CREATE TABLE Table1( column1 VARCHAR(5) CHARACTER SET latin1 COLLATE latin1_german1_ci); MySQL chooses the column character set and collation thus: If both CHARACTER SET X and ...
character_maximum_length reports a extremely high value, which does not seem to relate to reality: this is the table structure: CREATE TABLE `multiqueue` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `uuid` varchar(36) NOT NULL, `draft_uuid` varchar(36) DEFAULT NULL COMMENT ...
In this context, VARCHAR and CHAR are considered the same if they are declared as the same size. tt.ActualPC is declared as CHAR(10) and et.EMPLOYID is CHAR(15), so there is a length mismatch. To fix this disparity between column lengths, use ALTER TABLE to lengthen ActualPC from ...
(As of MySQL Version 3.23, the length of CHAR may be 0 to 255.) When CHAR values are stored, they are right-padded with spaces to the specified length. When CHAR values are retrieved, trailing spaces are removed. Values in VARCHAR columns are variable-length strings. You can declare a ...