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Deleting an Existing Row with DELETE Statements in SQL Server
How To Delete an Existing Row with DELETE Statements in SQL Server? If you want to delete an existing row from a table, you can use the DELETE statement with a WHERE clause to identify that row. Here is good sample of DELETE statements: -- insert a row for this test INSERT INTO fyi_links (url, id) V...
2016-10-30, 177👍, 0💬

Using Multiple Columns in the GROUP BY Clause in SQL Server
Can Multiple Columns Be Used in GROUP BY in SQL Server? If you want to break your output into smaller groups, you can specify multiple column names or expressions in the GROUP BY clause. Output in each group must satisfy a specific combination of the expressions listed in the GROUP BY clause. The mo...
2016-10-25, 177👍, 0💬

Triggers with Multiple Affected Rows in SQL Server
What Happens to a Trigger with Multiple Affected Rows in SQL Server? If there is only one row affected by a DML statement, we know that the DML trigger will be executed once. But how many times the DML trigger will be executed if the DML statement resulted multiple affected rows? The answer is still...
2016-10-24, 177👍, 0💬

"INSERTED" - New Record of an DML Event Instance in SQL Server
How To Access the Inserted Record of an Event in SQL Server? When a DML event occurs, SQL Server will prepare a temporary table called "INSERTED", which contains the new record of the affected row, which is: A copy of the inserted row for an INSERT statement. A copy of the updated row for an UPDATE ...
2016-10-24, 177👍, 0💬

"DELETED" - Old Record of an DML Event Instance in SQL Server
How To Access the Deleted Record of an Event in SQL Server? When a DML event occurs, SQL Server will prepare a temporary table called "DELETED", which contains the old record of the affected row, which is: A copy of the deleted row for a DELETE statement. A copy of the row to be updated for an UPDAT...
2016-10-24, 177👍, 0💬

"DROP LOGIN" - Deleting a Login Name in SQL Server
How To Delete a Login Name in SQL Server? If you don't want to keep a login name any more, you should delete it by using the "DROP LOGIN" statement as shown in this tutorial example: -- Login with "sa" DROP LOGIN Dba_Login; GO Command(s) completed successfully. -- View login names SELECT name, sid, ...
2016-10-19, 177👍, 0💬

Joining Two Tables in a Single Query in SQL Server
How To Join Two Tables in a Single Query in SQL Server? Two tables can be joined together in a query in 4 ways: Inner Join: Returns only rows from both tables that satisfy the join condition. Left Outer Join: Returns rows from both tables that satisfy the join condition, and the rest of rows from th...
2016-10-30, 176👍, 0💬

Testing DML Triggers in SQL Server
How To Test a DML Trigger in SQL Server? To test a DML trigger defined on a table, you just need to execute several INSERT, UPDATE and DELETE statements on that table as shown in this tutorial example: USE FyiCenterData; GO INSERT INTO fyi_users (name) VALUES ('FYI Admin'); GO Records are inserted, ...
2016-10-25, 176👍, 0💬

Turn on and off Autocommit in MySQL
How To Switch between Autocommit-On and Autocommit-Off Modes in MySQL? By default, your connection session will be in Autocommit-On mode, where every server executable statement will start a new transaction, and end the transaction when the execution ends. Changes will be committed. So consider this...
2016-10-17, 176👍, 0💬

Modes of Data Dump Export and Import in Oracle
What Are Data Pump Export and Import Modes in Oracle? Data Pump export and import modes are used to determine the type and portions of database to be exported and imported. Oracle 10g supports 5 export and import modes: Full: Exports and imports a full database. Use the FULL parameter to specify thi...
2016-10-15, 176👍, 0💬

Creating a Large Table with Random Data for Indexes in SQL Server
How To Create a Large Table with Random Data for Index Testing in SQL Server? If you want to see how index can be used to improve data search performance, you have to build some large tables, which requires large amount of random data. This tutorial exercise helps you to build a large table with pur...
2016-11-13, 175👍, 0💬

UPDATE Subquery Returning No Rows in SQL Server
What Happens If the UPDATE Subquery Returns No Rows in SQL Server? If you use a subquery to assign new values in the SET clause in an UPDATE statement, and the subquery returns no rows for an outer row, SQL Server will provide a NULL value to the SET clause. The tutorial exercise below shows you a g...
2016-11-02, 175👍, 0💬

Deleting Multiple Rows with One DELETE Statement in SQL Server
How To Delete Multiple Rows with One DELETE Statement in SQL Server? You can delete multiple rows from a table in the same way as deleting a single row, except that the WHERE clause will match multiple rows. The tutorial exercise below deletes 3 rows from the fyi_links table: -- view rows to be dele...
2016-10-30, 175👍, 0💬

"CREATE TRIGGER" - Creating a DML Trigger in SQL Server
How To Create a DML Trigger using CREATE TRIGGER Statements in SQL Server? A DML trigger is a trigger declared to handle a DML event, which occurs when an INSERT, UPDATE or DELETE statement is executed. If you want to create a DML trigger, you should use the "CREATE TRIGGER" statement in the followi...
2016-10-25, 175👍, 0💬

"CREATE SCHEMA" - Creating a New Schema in a Database in SQL Server
How To Create a New Schema in a Database in SQL Server? If you want to create a new schema in an existing database, you can use the "CREATE SCHEMA" statement as shown in the tutorial example below: USE FyiCenterData; GO CREATE SCHEMA fyi; GO Command(s) completed successfully. A new schema called "fy...
2016-10-22, 175👍, 0💬

"ALTER LOGIN" - Changing a Login Name in SQL Server
How To Change a Login Name in SQL Server? If you want to change a login name, you can use the "ALTER LOGIN" statement as shown in this tutorial example: -- Login with "sa" -- Change login name ALTER LOGIN Fyi_Login WITH NAME = Dba_Login; GO -- View login names SELECT name, sid, type, type_desc FROM ...
2016-10-19, 175👍, 0💬

UNION - Merging Outputs from Two Queries Together in SQL Server
How To Use UNION to Merge Outputs from Two Queries Together in SQL Server? If you have two queries that returns the same row fields, you can merge their outputs together with the UNION operator. The following tutorial exercise shows you how to use the UNION operator: SELECT * FROM fyi_links WHERE ta...
2016-10-26, 174👍, 0💬

Filtering Out Duplications in the Returning Rows in SQL Server
How To Filter Out Duplications in the Returning Rows in SQL Server? If there are duplications in the returning rows, and you want to remove the duplications, you can use the keyword DISTINCT in the SELECT clause. The DISTINCT applies to the combination of all data fields specified in the SELECT clau...
2016-10-26, 174👍, 0💬

sys.trigger_events - Event List of an Existing Trigger in SQL Server
How To See the Event List of an Existing Trigger using sys.trigger_events in SQL Server? If what are the DML events an existing trigger is handling, you can use the catalog view, sys.trigger_events. You need to join sys.trigger_events and sys.triggers to get a better list as shown in this tutorial e...
2016-10-24, 174👍, 0💬

Finding the Login Name Linked to a Given User Name in SQL Server
How To Find the Login Name Linked to a Given User Name in SQL Server? If you know a user name in a database and you want to find out which login name is linked this user name, you need to check the Security ID (SID) of the user name based on the following rules: Each login name is associated a uniqu...
2016-10-18, 174👍, 0💬

What Is CSV in MySQL
What Is CSV in MySQL? CSV (Comma Separated Values) is a file format used to store database table contents, where one table row is stored as one line in the file, and each data field is separated with comma.   ⇒Database Basics and Terminologies in MySQL ⇒⇒MySQL Database Tutorials
2016-10-16, 174👍, 0💬

Constant or Data Literal in SQL Server Transact-SQL
What Is a Constant or Literal in SQL Server Transact-SQL? A constant, or data literal, is a symbolic expression that represents a specific value of a specific data type in SQL Server Transact-SQL. Constants or literals are used commonly as the default values for table columns, variables, and paramet...
2017-05-20, 173👍, 0💬

Inserting Multiple Rows with One INSERT Statement in SQL Server
How To Insert Multiple Rows with One INSERT Statement in SQL Server? If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. The following tutorial exercise gives you a...
2016-11-02, 173👍, 0💬

Using Group Functions in the SELECT Clause in SQL Server
How To Use Group Functions in the SELECT Clause in SQL Server? If group functions are used in the SELECT clause, all rows that meet the criteria defined in the WHERE clause will be treated as a single group. The group functions will be apply all rows in that group as a whole. The final output of the...
2016-10-25, 173👍, 0💬

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