BEGIN TRANSACTION; -- This SELECT statement will acquire an IS lock on the table. SELECT col1 FROM TestTable WITH (HOLDLOCK); 会话2: 事务启动,并且在此事务下运行的 SELECT 语句将获取共享锁 (S) 并将其保留在表中。 将获取所有分区的 S 锁,这将产生多个表锁,每个分区一个。 例如,...
3. Calculating average with CASE WHEN CASE WHEN is like an IF statement in a programming language. It is useful when we need to calculate a statistic on a certain subset of the data. In the image above, I calculate an average price for products sold in the US. I wasn’t careful with...
ASELECT INTOstatement always creates a single-threaded insert operation.ASELECT INTOstatement can create a parallel insert operation. When inserting a large number of rows, the parallel operation can improve performance. Differences between lower compatibility levels and levels 10...
selectcolumnsfromtablewheretest_column[not]like'pattern'escape"escape_char"; 8.between and , in , in null wheretest_columnbetweenlow_valueandhign_value wheretest_columnin(value1,value2,value3) wheretest_columnis[not]null 二、操作符和函数 源自列的值、由系统确定的值、常数和其他数据的结果,可以...
serveris running with the --secure-file-priv option so it cannot execute this statement 处理: sed -i '/\[mysqld\]/a securefilepriv=/tmp' /etc/my.cnf systemctl restart mysqld MySQL 运算符 本章节我们主要介绍 的运算符运算符的优先级。 MySQL 主要有以下几种运算符: 算术符 ...
CREATE DATABASE between_in_db; Copy If the database was created successfully, you’ll receive output like this: Output Query OK, 1 row affected (0.01 sec) To select thebetween_in_dbdatabase, run the followingUSEstatement: USE between_in_db; ...
A SELECT INTO statement always creates a single-threaded insert operation. A SELECT INTO statement can create a parallel insert operation. When inserting a large number of rows, the parallel operation can improve performance. Differences between lower compatibility levels and levels 100 and 110 This ...
The SQL BETWEEN condition allows you to easily test if an expression is within a range of values (inclusive). It can be used in a SELECT, INSERT, UPDATE, or DELETE statement. Subscribe Syntax The syntax for the BETWEEN condition in SQL is: ...
We regularly insert data into SQL Server tables either from an application or directly in SSMS. We can insert data using the INSERT INTO statement. To do this, we should have a table already in place to insert data into it as we cannot create a table using Insert into the statement. ...
函数和多个SELECT语句通过select_statement分隔UNION或UNION ALL可用于。 CHECK OPTION 要求对该视图执行的所有数据修改语句都必须符合 select_statement 中所设置的条件。 通过视图修改行时, WITH CHECK OPTION 请确保在提交修改后通过视图保持可见数据。 备注 CHECK OPTION仅适用于通过视图进行的更新。 它不适用于直接对...