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Updating Values with UPDATE Statements in SQL Server
How To Update Values in a Table with UPDATE Statements in SQL Server? If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: SELECT * FROM fyi_links WHERE id = 101 GO id url notes counts created 101 ...
2016-11-02, 288👍, 0💬

Sorting Query Output in Descending Order in SQL Server
How To Sort Query Output in Descending Order in SQL Server? 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: SELECT tag, cou...
2016-10-26, 288👍, 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, 288👍, 0💬

Improving the Trigger to Handle NULL Values in SQL Server
How To Improve the Trigger to Handle NULL Values in SQL Server? When a NULL value is concatenated with a string, the result will be a null value. So if you want the trigger to properly report NULL values, you need to enhance the trigger as shown in the following tutorial example: USE FyiCenterData; ...
2016-10-24, 288👍, 0💬

Show Installed Oracle ODBC Drivers in Oracle
How To Find Out What Oracle ODBC Drivers Are Installed in Oracle? To find out what Oracle ODBC drivers are installed on your Windows system, you can use the ODBC manager to look at them: Go to Control Panel. Go to Administrative Tools. Run Data Sources (ODBC). Go to System DSN tab. Click the Add but...
2016-10-15, 288👍, 0💬

Decrementing a Date by 1 in MySQL
How To Decrement Dates by 1 in MySQL? If you have a date, and you want to decrement it by 1 day, you can use the DATE_SUB(date, INTERVAL 1 DAY) function. You can also use the date interval subtraction operation as "date - INTERVAL 1 DAY". The tutorial exercise below gives you some good examples: SEL...
2017-12-26, 287👍, 0💬

Defining and Using Table Alias Names in SQL Server
How To Define and Use Table Alias Names in SQL Server? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names. To define an alias for a table name, just enter the alias name right after the original table name in the FROM clause as...
2016-10-30, 287👍, 0💬

Default Schema of Your Login Session in SQL Server
What Is the Default Schema of Your Login Session in SQL Server? When you login to a SQL Server and select a database to use, SQL Server will assign your login session a default schema. The schema name can be omitted when you refer to objects in the default schema. Here is what you should remember ab...
2016-10-22, 287👍, 0💬

Declaring and Using Cursor Variables in SQL Server
How To Declare and Use Cursor Variables in SQL Server Transact-SQL? There are two ways to representing a cursor: 1. A cursor name - A static name representing a cursor object. A cursor name should be linked to a cursor object in the DECLARE statement. 2. A cursor variable name - A variable name poin...
2016-10-17, 287👍, 0💬

Moving Database Physical Files to New Locations in SQL Server
How to move database physical files in SQL Server? If you want to move database physical files to a new location, you can use the "ALTER DATABASE" statements to bring the database offline, and link it to the files at the new location. The following tutorial gives you a good example: ALTER DATABASE F...
2016-11-20, 286👍, 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, 286👍, 0💬

Show All Indexes of a given Table in MySQL
How To Get a List of Indexes of a Given Table in MySQL? If you want to see the index you have just created for an existing table, you can use the "SHOW INDEX FROM tableName" command to get a list of all indexes in a given table. The tutorial script below shows you a nice example: mysql&gt; SHOW ...
2018-02-14, 285👍, 0💬

Returning Query Output in HTML Format in MySQL
How To Return Query Output in HTML Format in MySQL? By default, "mysql" returns query output in text table format. If you want to receive query output in HTML format, you need to use the "-H" command option. Here is a good tutorial exercise: &gt;cd \mysql\bin &gt;mysql -u root -H test mysql&...
2018-02-08, 285👍, 0💬

Using Subqueries in the FROM Clause in MySQL
How To Use Subqueries in the FROM clause in MySQL? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. A subquery used in this way become a temporary table, and you mus...
2017-12-21, 285👍, 0💬

Primary Key - Default Indexes of Tables in SQL Server
Is the PRIMARY KEY Column of a Table an Index in SQL Server? If you define a primary key on a table, an index for the primary key column will be created by default. The tutorial exercise below shows you the index created as part of the primary key column of "fyi_links": USE FyiCenterData; GO -- Drop...
2016-11-13, 285👍, 0💬

Deleting All Rows with DELETE Statements in SQL Server
How To Delete All Rows with DELETE Statements in SQL Server? 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. Here is an example of deleting all rows with a DELETE statement: SELECT COUNT(*) FROM fyi_l...
2016-10-30, 285👍, 0💬

"FETCH" - Fetching the Next Row from a Cursor in SQL Server
How To Fetch the Next Row from a Cursor with a "FETCH" Statement in SQL Server Transact-SQL? When the result set is ready in a cursor, you can use a FETCH statement to retrieve one row from the result set in the same format as a SELECT statement. The FETCH statement has the following formats: FETCH ...
2016-10-17, 285👍, 0💬

What Is Transaction in MySQL
What Is Transaction in MySQL? A transaction is a logical unit of work requested by a user to be applied to the database objects. MySQL server introduces the transaction concept to allow users to group one or more SQL statements into a single transaction, so that the effects of all the SQL statements...
2016-10-16, 285👍, 0💬

Define Anonymous Procedures without Variables in Oracle
How To Define an Anonymous Procedure without Variables in Oracle? Anonymous procedure is a procedure without any name. If you don't have any variables to declare, you can define an anonymous procedure by using the BEGIN keyword directly in SQL*Plus as shown in the following tutorial script: SQL&...
2018-01-27, 284👍, 0💬

Calculating the Difference between Two Time Values in MySQL
How To Calculate the Difference between Two Time Values in MySQL? If you have two time values, and you want to know the time difference between them, you can use the TIMEDIFF(time1, time2) function as shown below: SELECT TIMEDIFF(TIME('19:26:50'), TIME('09:26:50')) FROM DUAL; 10:00:00 SELECT TIMEDIF...
2017-12-26, 284👍, 0💬

Memory Usage of the MySQL Server in MySQL
How Much Memory Does the Server Take in MySQL? If you are interested to know how much memory your MySQL server is taking, you can use Windows Task Manager to find out. Try to following this tutorial exercise: Start your MySQL server. Press Ctrl-Alt-Del and click Task Manager. The Task Manager window...
2017-12-04, 284👍, 0💬

Getting a List of All Databases on the Server in SQL Server
How to get a list all databases on the SQL server in SQL Server? If you don't remember database names you have created, you can get a list of all databases on the server by query the "sys.databases" view as shown in this tutorial example: CREATE DATABASE FyiCenterData GO SELECT name, database_id, cr...
2016-11-24, 284👍, 0💬

DROP VIEW - Deleting Existing Views in SQL Server
How To Drop Existing Views from a Database in SQL Server? If you don't need a specific view any more, you can use the DROP VIEW statement to delete it from the database. The following tutorial exercise shows you how to delete the view, fyi_links_view: USE FyiCenterData; GO SELECT * FROM sys.views; G...
2016-11-05, 284👍, 0💬

UPDATE Subquery Returning Multiple Rows in SQL Server
What Happens If the UPDATE Subquery Returns Multiple Rows in SQL Server? If a subquery is used in a UPDATE statement, it must return exactly one row for each row in the update table that matches the WHERE clause. If it returns multiple rows, SQL Server will give you an error message. To test this ou...
2016-11-02, 284👍, 0💬

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