TRUNCATE statement: This command is used to delete all the rows from the table and free the space containing the table.SQL DROP Statement:The SQL DROP command is used to remove an object from the database. If you drop a table, all the rows in the table is deleted and the table ...
The SELECT statement just gives us a sample of the data in the table. We can use the TOP command to limit the number of rows returned. What is more interesting is thesp_spaceusedstored procedure. It tells us useful information such as reserved space, data space, and index space in kiloby...
As you may have guessed, we can return the opposite values (rows) of our previous query (see section “SQL WHERE IN with a Subquery”) by simply adding the NOT operator in the WHERE IN clause. This will return all first names, last names, and SalesQuotas that are less than 300,000.00...
According to Microsoft documentation, the Delete statement removes one or more rows from a table or view in SQL Server. One might wonder how the statement defines whether to remove some or all of the data (rows) from a table. The answer lies in the criteria or conditions specifying what ne...
AND Context IN ('LCX_TEXT_MIX') AND Operation in ('LOP_DELETE_ROWS') /*Use this subquery to filter the date*/ AND [TRANSACTION ID] IN (SELECT DISTINCT [TRANSACTION ID] FROM sys.fn_dblog(NULL, NULL) WHERE Context IN ('LCX_NULL') AND Operation in ('LOP_BEGIN_XACT') And [Transac...
一.在mssql 里头实现同步镜像,只能主库用而镜像库不能同时用,而mysql 主从同步可以实现 数据库的读写分离,主库负责 update insert delete ,从库负责select 这样一来具有相应的优点: (1) 数据分布 (Data distribution ) (2) 负载平衡(load balancing) (3) 备份(Backups) (4) 高可用性和容错行 High availab...
sql insert、update、delete完以后返回主键ID 以前只用过在insert完以后利用select @@IDENTITY返回主键ID,最近在做微信公众平台,遇到一个需求是在帮绑定万微信openid后自动完成登陆,这就需要update以后返回主键ID,查了一些资料找到了output这一解决方案。 update [SmartPromoter] set [Name]='aaaaaaaa' outputDELETED.[...
T-SQL GETDATE() ? ADD and SUBTRACT depending on the condition is CASE STATEMENT ADD COLUMN to variable table? Add prefix in data column Add Time in SQL HH:MM:SS to another HH:MM:SS Adding a column to a large (100 million rows) table with default constraint adding a extra column in...
SQL delete duplicate Rows using Common Table Expressions (CTE) We can use Common Table Expressions commonly known as CTE to remove duplicate rows in SQL Server. It is available starting from SQL Server 2005. We use a SQLROW_NUMBERfunction, and it adds a unique sequential row number for the...
Let’s understand why it is essential to remove unwanted columns from the SQL table. Below is my table structure and we need to remove column having data type varchar(2000). This table contains 4 million rows, and the user executed the command to select all records from this table. ...