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Providing Column Names in INSERT Statements in SQL Server
How to provide column names in INSERT Statements in SQL Server? If you don't want to specify values for columns that have default values, or you want to specify values to columns in an order different than how they are defined, you can provide a column list in the INSERT statement. If a column is om...
2016-11-02, 345👍, 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, 345👍, 0💬

"GROUP BY" - Dividing Query Output into Multiple Groups in SQL Server
How To Divide Query Output into Multiple Groups with the GROUP BY Clause in SQL Server? Sometimes, you want to divide the query output into multiple groups, and apply group functions on each individual groups. Dividing query output into multiple groups can be done with the GROUP BY clause. Here is t...
2016-10-25, 345👍, 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, 342👍, 0💬

Mixing Group Functions with Non-group Selection Fields in SQL Server
Can Group Functions Be Mixed with Non-group Selection Fields in SQL Server? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of inva...
2016-10-25, 342👍, 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, 341👍, 0💬

Creating an Index on a View in SQL Server
How To Create an Index on a View in SQL Server? If you need to search and sort data in a view with a large number of row, you may want to create an index on the view to speed up your search process. The tutorial exercise below shows you how to create a unique clustered index on a view. DROP VIEW fyi...
2016-11-03, 341👍, 0💬

Adding More Test Data for Query Statements in SQL Server
How To Add More Data to the Testing Table in SQL Server? If you want to continue with other tutorial exercises in this FAQ collection, you need to add more data to the testing table. Follow the script below to add a new column and more rows: ALTER TABLE fyi_links ADD tag VARCHAR(8) GO UPDATE fyi_lin...
2016-10-26, 341👍, 0💬

Using LIKE Conditions in MySQL
How To Use LIKE Conditions in MySQL? A LIKE condition is also called pattern patch. There are 3 main rules on using LIKE condition: '_' is used in the pattern to match any one character. '%' is used in the pattern to match any zero or more characters. ESCAPE clause is used to provide the escape char...
2018-03-24, 340👍, 0💬

Simplest Way To Create New Databases in SQL Server
What is the simplest way to create a new database in SQL Server? The simplest way to create a new database is to use the "CREATE DATABASE" statement with this syntax: CREATE DATABASE database_name For example, run this statement: CREATE DATABASE FyiCenterData GO A new database called "FyiCenterData"...
2016-11-24, 340👍, 0💬

"DROP TABLE" - Deleting Existing Tables in SQL Server
How To Drop an Existing Table with "DROP TABLE" Statements in SQL Server? If you want to delete an existing table and its data rows, you can use the "DROP TABLE" statement as shown in the tutorial script below: SELECT * FROM tipBackup GO id subject description create_date 1 Learn SQL Visit dev.fyice...
2016-11-15, 337👍, 0💬

HAVING - Apply Filtering Criteria at Group Level in SQL Server
How To Apply Filtering Criteria at Group Level with The HAVING Clause in SQL Server? Let's say you have divided the query output into multiple groups with the GROUP BY clause. Now you are only interested in some of the groups, not all the groups. If you want to filter out some groups from the query,...
2016-10-25, 332👍, 0💬

Initialize Variables with Default Values in Oracle
How To Initialize Variables with Default Values in Oracle? There are two ways to assign default values to variables at the time of declaration: Using key word DEFAULT - Appending "DEFAULT value" to the end of declaration statements. Using assignment operator - Appending ":= value" to the end of decl...
2018-08-06, 324👍, 0💬

Inserting Data into a View in SQL Server
Can You Insert Data into a View in SQL Server? Can you insert data into a view? The answer is no. But if the question is "Can you insert data into the underlying table through view?" The answer is then yes. SQL Server will allow you to insert data into the underlying table through a view with a cond...
2016-11-04, 316👍, 0💬

Selecting Some Specific Rows from a Table in SQL Server
How To Select Some Specific Rows from a Table in SQL Server? If you don't want select all rows from a table, you can specify a WHERE clause to tell the query to return only the rows that meets the condition defined in the WHERE clause. The WHERE clause condition is a normal Boolean expression. If an...
2016-10-26, 311👍, 0💬

Define a RECORD Variable for a Table Row in Oracle
How To Define a RECORD Variable to Store a Table Row in Oracle? If you have a table, and want to define a RECORD variable to store all the data elements of a row from that table, you can use table_name%ROWTYPE to define the RECORD variable as shown in the following sample script: CREATE TABLE studen...
2018-08-14, 309👍, 0💬

Ways to End the Current Transaction in MySQL
How To End the Current Transaction in MySQL? There are several ways the current transaction can be ended implicitly or explicitly: In "Autocommit On" mode, a single-statement transaction will be ended implicitly when the execution of the statement ends. Changes will be committed. Running the COMMIT ...
2016-10-17, 306👍, 0💬

Entering Boolean Values in MySQL
How To Enter Boolean Values in SQL Statements in MySQL? If you want to enter Boolean values in SQL statements, you use (TRUE), (FALSE), (true), or (false). Here are some good examples: SELECT TRUE, true, FALSE, false FROM DUAL; +------+------+-------+------- +| TRUE | TRUE | FALSE | FALSE | +------+...
2018-03-31, 303👍, 0💬

What Is a Subquery in a SELECT Query Statement in SQL Server
What Is a Subquery in a SELECT Query Statement in SQL Server? A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The output of the subquer...
2016-10-29, 302👍, 0💬

Updating Multiple Rows with One UPDATE Statement in SQL Server
How To Update Multiple Rows with One UPDATE Statement in SQL Server? If the WHERE clause in an UPDATE statement matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example: SELE...
2016-11-02, 282👍, 0💬

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