NULL isn't zero or blank: NULL means no entry was made or an explicit NULL was supplied, and it typically implies that the value is either unknown or not applicable. When you use CREATE TABLE or ALTER TABLE to create or alter a table, database and session settings influence and possibly...
If NAME is not specified, it is blank. { EXPIREDATE ='date' | RETAINDAYS = days } Specifies when the backup set for this backup can be overwritten. If these options are both used, RETAINDAYS takes precedence over EXPIREDATE. If neither option is specified, the expiration date is ...
Null is a value that is unavailable, unassigned(未赋值), unknown, or inapplicable(不适用的). Null is not the same aszero(数值类型的0)or ablank space(字符类型的空格). 包含NULL值的算术表达式,其结果还是NULL. If a column doesn't has a definite value, it is considered as NULL. NULL value...
标准的字符类名字是:alnum、 alpha、blank、 cntrl、digit、 graph、lower、 print、punct、 space、upper、 xdigit。 它们代表在ctype中定义的字符类。 一个区域可以会提供其他的类。字符类不能用做一个范围的端点。 方括号表达式里有两个特例:方括号表达式[[:<:]]和[[:>:]]是约束,分别匹配一个单词开头和结...
UNIQUE and PRIMARY KEY constraints are always enforced. When importing into a character column that is defined with a NOT NULL constraint, BULK INSERT inserts a blank string when there's no value in the text file. At some point, you must examine the constraints on the whole table. If the...
If NAME is not specified, it is blank. { EXPIREDATE ='date' | RETAINDAYS = days } Specifies when the backup set for this backup can be overwritten. If these options are both used, RETAINDAYS takes precedence over EXPIREDATE. If neither option is specified, the expiration date is ...
Displays the specified text then waits for the user to press RETURN. PRO[MPT] [text] Sends the specified message or a blank line to the user's screen. UNDEF[INE] variable ... Deletes one or more substitution variables that you defined either explicitly (with the DEFINE command) or implic...
(must contain useable space) for the CREATE DATABASE command to succeed. The physical hard drive letter is specified in the database manager configuration. If DFTDBPATH is left blank the default will be the hard drive where the database product is installed on the instance-owning machine (...
If you want to change the DIR_TYPE value, make sure the DIR_PATH_NAME and DIR_OBJ_NAME parameters have been specified with the valid values first. If you want to blank out either the DIR_PATH_NAME or the DIR_OBJ_NAME parameter, make sure you set DIR_TYPE to NONE first. ...
01004 String data, right truncated String or binary data returned for a column resulted in the truncation of nonblank character or non-NULL binary data. If it was a string value, it was right-truncated. 01S01 Error in row An error occurred while fetching one or more rows. (If this SQL...