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Creating Triggers for INSERT Statements Only in SQL Server
How To Create a Trigger for INSERT Only in SQL Server? The trigger, dml_message, provided in previous tutorials was defined to handle all 3 types of DML statements, INSERT, UPDATE, and DELETE. If you do not want the trigger to handle all 3 types of DML statements, you can list only 1 or 2 of the sta...
2016-10-24, 676👍, 0💬

Create Tables for ODBC Connection Testing in Oracle
How To Create Tables for ODBC Connection Testing in Oracle? If you want to follow the tutorial exercises in the sections below, you need to create a user account and a table for ODBC connection testing as shown here: SQL&gt; CONNECT system/retneciyf Connected. SQL&gt; CREATE USER fyi IDENTIF...
2016-10-15, 676👍, 0💬

Use "FOR" Loop Statements in Oracle
How To Use "FOR" Loop Statements in Oracle? If you have a block of codes to be executed repeatedly over a range of values, you can use the "FOR ... LOOP" statement. Here is a sample script on FOR statements: DECLARE total NUMBER := 0; BEGIN FOR i IN 1..10 LOOP total := total + i; END LOOP; DBMS_OUTP...
2018-07-13, 675👍, 0💬

Creating a View with Data from Another View in SQL Server
Can You Create a View using Data from Another View in SQL Server? Can You Create a View with Data from Another View? The answer is yes. A view can be used as a table to build other views. The tutorial exercise below shows you how to create a view using data from another view: USE AdventureWorksLT; G...
2016-11-05, 675👍, 0💬

Using Group Functions in the ORDER BY Clause in SQL Server
Can Group Functions Be Used in the ORDER BY Clause in SQL Server? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns the maximum "counts" in each group, determined by a unique combination of tag and ye...
2016-10-25, 675👍, 0💬

Name Conflicts between Variables and Columns in Oracle
How To Resolve Name Conflicts between Variables and Columns in Oracle? The best way to resolve name conflicts is to avoid using column names for variables.   ⇒Working with Database Objects in Oracle PL/SQL ⇒⇒Oracle Database Tutorials
2018-09-24, 674👍, 0💬

Selecting an Existing Database in MySQL
How To Select an Exiting Database in MySQL? The first thing after you have created a connection object to the MySQL server is to select the database where your tables are located, by using the mysql_select_db() function. If your MySQL server is offered by your Web hosting company, they will assign a...
2017-10-23, 674👍, 0💬

Deleting an Existing Database in MySQL
How To Drop an Existing Database in MySQL? If want to drop an existing database from the MySQL server, you can use the DROP DATABASE statement. Here is a good example of dropping an existing database: $con = mysql_connect('localhost:8888' ,'dev', 'iyf'); $sql = 'DROP DATABASE fyi'; if (mysql_query($...
2017-10-23, 674👍, 0💬

Assign Names to Query Output Columns in MySQL
How To Name Query Output Columns in MySQL? Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example: mysql&gt; SELECT tag AS Categ...
2017-09-28, 674👍, 0💬

CREATE INDEX - Impact on Other User Sessions in SQL Server
What Is the Impact on Other User Sessions When Creating Indexes in SQL Server? If you are creating a new index on a table with existing data, all existing rows will be indexed as part of the CREATE INDEX statement. If the table is large, the indexing process could take some time. The impact of this ...
2016-11-08, 674👍, 0💬

Using Group Functions in the ORDER BY Clause in MySQL
Can Group Functions Be Used in the ORDER BY Clause in MySQL? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many links were created in each year in each tag. The group output is sorted by the c...
2017-12-31, 673👍, 0💬

Understanding and Managing Indexes in SQL Server
Where to find answers to frequently asked questions on Understanding and Managing Indexes in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Understanding and Managing Indexes in SQL Server. Clear answers are provided with tutorial exe...
2016-11-15, 673👍, 0💬

"ALTER LOGIN" - Changing the Password of a Login Name in SQL Server
How To Change the Password of a Login Name in SQL Server? If a developer lost the password of his or her login name, you can reset the password with the "ALTER LOGIN" statement as shown in this tutorial example: -- Login with sa ALTER LOGIN FYI_DBA WITH PASSWORD = 'fyicenter'; GO Command(s) complete...
2016-10-20, 673👍, 0💬

Sort Query Output in Descending Order in Oracle
How To Sort Query Output in Descending Order in Oracle? If you want to sort a column in descending order, you can specify the DESC keyword in the ORDER BY clause. The following SELECT statement first sorts the department in descending order, then sorts the salary in ascending order: SQL&gt; SELE...
2019-12-19, 672👍, 0💬

Filerting out Duplications in Returning Rows in MySQL
How To Filter Out Duplications in Returning Rows in MySQL? 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 clause. The t...
2018-01-06, 672👍, 0💬

User Privilege Tables in MySQL
Where Are User Privileges Stored on the Server in MySQL? MySQL server has a system database, which hosts a number of system tables to system related information like user privileges. Depending on the scope levels, granted user privileges are stored in different tables: "mysql.user" - Stores privileg...
2017-12-09, 672👍, 0💬

Sorting Output in Descending Order in MySQL
How To Sort Output in Descending Order in MySQL? If you want to sort a column in descending order, you can specify the DESC keyword in the ORDER BY clause. The following SELECT statement first sorts the "tag" in descending order, then sorts the "counts" in ascending order: mysql&gt; SELECT tag, ...
2017-11-02, 672👍, 0💬

Filter Out Duplications in Returning Rows in Oracle
How To Filter Out Duplications in Returning Rows in Oracle? If there are duplications in the returning rows, and you want to remove the duplications, you can use the keyword DISTINCT or UNIQUE in the SELECT clause. The tutorial exercise below shows you that DISTINCT works on selected columns only: S...
2019-12-19, 671👍, 0💬

Database in Use When Renaming a Database in SQL Server
Why I am getting this error when renaming a database in SQL Server? If you are trying to rename a database that is in use, you will get an error message like this: "The database could not be exclusively locked to perform the operation." Before renaming a database, you must stop all client sessions u...
2016-11-20, 671👍, 0💬

System Databases Used by SQL Servers in SQL Server
What are system databases in SQL Server? System databases are created by the SQL Server itself during the installation process. System databases are used by the SQL server to help manage other user databases and client execution sessions. SQL Server 2005 Express Edition uses 4 system databases: mast...
2016-11-20, 671👍, 0💬

Testing Table for DML Statements in SQL Server
How To Create a Testing Table with Test Data in SQL Server? If you want to practice DML statements, like INSERT, UPDATE and DELETE statements, you should create a testing table. The tutorial exercise shows you a good example: CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url VARCHAR(80) NOT NULL, ...
2016-11-03, 671👍, 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, 671👍, 0💬

in Oracle
How To Delete All Rows from a Table in Oracle? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise shows you a good exa...
2020-01-04, 670👍, 0💬

Retrieve the Count of Updated Rows in Oracle
How To Retrieve the Count of Updated Rows in Oracle? After running an UPDATE statement, the database server returns a count of updated rows. You can retrieve this count from a special predefined variable called SQL%ROWCOUT, as shown in the following tutorial: CREATE TABLE emp_temp AS SELECT * FROM e...
2018-09-13, 670👍, 0💬

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