下面就通过各种语句,来获取索引的状态,动态调整索引,及时添加或清理失效的索引。...(仅仅在MYSQL8 中作用,information_schema) select it.name,ii.index_count from innodb_tables as it inner join...sys.statements_with_runtimes_in_95th_percentile where query like 'select%'; 以上的信息都可以帮助DB 人员...
慢查询日志概念 MySQL的慢查询日志是MySQL提供的一种日志记录,它用来记录在MySQL中响应时间超过阀值的语句,具体指运行时间超过long_query_time值的SQL,则会被记录到慢查询日志中...默认情况下,Mysql数据库并不启动慢查询日志,需要我们手动来设置这个参数,当然,如果不是调优需要的话,一般不建议启动该参数,因为开启慢查...
ALTER TABLE ADD CONSTRAINT UNIQUE(); 实例2,修改数据表 demo_department,指定部门的名称唯一,输入的 SQL 语句和运行结果如下所示。 mysql> ALTER TABLE demo_department -> ADD CONSTRAINT unique_name UNIQUE(name); Query OK, 0 rows affected (0.63 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> DES...
To help identifying table candidates that are using uniqueifiers (heavily or not), you can leverage the following query: 复制 SELECT OBJECT_NAME(I.object_id) AS ObjectName , I.object_id , I.name AS IndexName , I.is_unique , C.name AS ColumnName , T.name AS TypeName , C.max_len...
【实例2】把学生表student的name唯一约束删除,输入的 SQL 语句和运行结果如下所示。 mysql> alter table student drop index name; Query OK, 0 rows affected Records: 0 Duplicates: 0 Warnings: 0 mysql> desc student; +---+---+---+---+---+---+ | Field | Type | Null | Key | Default ...
In Object Explorer, connect to an instance of Database Engine. On the Standard bar, select New Query. Copy and paste the following example into the query window and select Execute. The example creates a table and defines a unique constraint on the column TransactionID. SQL Afrita USE ...
Verification Now, let us list all the indexes that are created on the CUSTOMERS table using the following query − SHOWINDEXFROMCUSTOMERS; As you observe you can find the column names NAME, and AGE along with the ID (PRIMARY KEY) in the list of indexes. ...
colon(:) in query string Combine image with text in dropdownlist? Combine two regular expression Compare Dropdownlist selected value Compare Old and New Text of TextBox Compare two DataTables and return 3rd with Difference Compare Validator for Dates Compiler Error Message: CS0234: The type or name...
Take note of the result of the above SQL query. Proceed with safely deleting one of the duplicated user ids. Run the below queries in order: 1234DELETE FROM cwd_membership WHERE child_user_id = <duplicated_id>; DELETE FROM cwd_user_attribute WHERE user_...
You can set the UniqueValues property in the query's property sheet or in SQL view of the Query window. Note: You can set this property when you create a new query by using an SQL statement. The DISTINCT predicate corresponds to the UniqueValues property setting. The DISTINCTROW predicate ...