SELECT * FROM table_name WHERE column_name LIKE '%foo%' OR column_name LIKE '%bar%' OR column_name LIKE '%baz%' AND column_name NOT LIKE '%qux%'; 在上面的查询中,使用IN运算符将三个like子句连接起来,并使用“AND”关键字将三个like子句与一个“NOT LIKE”子句组合起来,以排除匹配“qux”...
但是更新操作UPDATE,INSERT,DELETE还不能并行处理。 8、如果是使用like进行查询的话,简单的使用index是不行的,但是全文索引耗空间。 like ‘a%’ 使用索引 like ‘%a’ 不使用索引用 like ‘%a%’ 查询时,查询耗时和字段值总长度成正比,所以不能用CHAR类型,而是VARCHAR。对于字段的值很长的建全文索引。
SELECT * FROM sys.dm_os_memory_clerks WHERE name LIKE '%plans%'; 备注 计划缓存有两个不用于存储计划的附加存储: “绑定树”缓存存储区 (PHDR),用于在视图、约束和默认值的计划编译期间使用的数据结构。 这些结构称为绑定树或 Algebrizer 树。 “扩展存储过程”缓存存储 (XPROC),用于预定义的系统过程(...
mysql>SHOW VARIABLES LIKE "secure_file_priv"; +---+---+ | Variable_name | Value | +---+---+ | secure_file_priv | | +---+---+这里secure_file_priv的值要为""或者 "/" secure_file_priv 有三个值1、限制 mysqld 不允许导入 | 导出mysqld –secure_file_prive=null2、限制 mysqld...
completion Generate the autocompletion script for the specified shell config Modify sqlconfig files using subcommands like "sqlcmd config use-context mssql" create Install/Create SQL Server, Azure SQL, and Tools delete Uninstall/Delete the current context help Help about any command open Open tools...
key_buffer_size指定索引缓冲区的大小,它决定索引处理的速度,尤其是索引读的速度。通过检查状态值Key_read_requests和Key_reads,可以知道key_buffer_size设置是否合理。比例key_reads / key_read_requests应该尽可能的低,至少是1:100,1:1000更好(上述状态值可以使用SHOW STATUS LIKE ‘key_read%’获得)。
wildcard characters. During pattern matching, regular characters must exactly match the characters specified in the character string. However, wildcard characters can be matched with arbitrary fragments of the character string. Using wildcard characters makes theLIKEoperator more flexible than using the=...
SELECT q.query_id, qt.query_sql_text FROM sys.query_store_query_text qt INNER JOIN sys.query_store_query q ON qt.query_text_id = q.query_text_id WHERE query_sql_text like N'%ORDER BY ListingPrice DESC%' AND query_sql_text not like N'%query_store%'; GO 下面的示例应用了提示,...
This option lets you enable a plan-affecting trace flag only during single-query compilation. Like other query-level options, you can use it together with plan guides to match the text of a query being executed from any session...
%Any string of zero or more characters.WHERE title LIKE '%computer%'finds all book titles with the wordcomputeranywhere in the book title. _(underscore)Any single character.WHERE au_fname LIKE '_ean'finds all four-letter first names that end withean(Dean,Sean, and so on). ...