General MySQL Oracle SQL Server

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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, 2510🔥, 0💬

Defragmenting Table Indexes in SQL Server
How To Defragment Table Indexes in SQL Server? When a table index is fragmented to a certain percentage, you need to defragment the index to maintain its performance level. There are 3 ways to defragment: 1. "ALTER INDEX index_name ON table_name REORGANIZE" - Defragmenting the specified index perfor... 2016-11-08, 2510🔥, 0💬

What Are Group Functions in MySQL
What Are Group Functions in MySQL? Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each row of the group. MAX(exp) - Returns the maximum ... 2018-01-06, 2509🔥, 0💬

PHP ODBC - Updating Existing Rows in a Table
PHP ODBC - How To Update Existing Rows in a Table? Updating existing rows in a table requires to run the UPDATE statement with a WHERE clause to identify the row. The following sample script updates one row with two new values: &lt;?php $con = odbc_connect('FYI_SQL_SERVER', 'sa','FYIcenter');$sq... 2024-05-29, 2508🔥, 0💬

Drop an Existing Table in MySQL
How To Drop an Existing Table in MySQL? 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: mysql&gt; SELECT * FROM tipBackup; +----+-------------+---------- ---------------+-------------+| id | subject | descri... 2018-02-14, 2508🔥, 0💬

PHP MSSQL - Searching Records by Keywords
PHP MSSQL - How To Perform Key Word Search in Tables? The simplest way to perform key word search is to use the SELECT statement with a LIKE operator in the WHERE clause. The LIKE operator allows you to match a text field with a keyword pattern specified as '%keyword%', where (%) represents any numb... 2024-02-09, 2505🔥, 0💬

Expressions with NULL Values in MySQL
What Happens If NULL Values Are Involved in Expressions in MySQL? If NULL values are used in expressions, the resulting values will be NULL values. In other words: Arithmetic expressions with NULL values result NULL values. Comparison expressions with NULL values result NULL values. Logical expressi... 2018-03-28, 2504🔥, 0💬

Returning the Second 5 Rows in MySQL
How To Return the Second 5 Rows in MySQL? If you want to display query output in multiple pages with 5 rows per page, and the visitor wants to see the output for the second page, you need to display query output from row 6 to row 10. You can use the "LIMIT startRow maxRows" clause to return only row... 2017-12-21, 2503🔥, 0💬

How Data Locks Are Respected in Oracle
How Data Locks Are Respected in Oracle? Here are the rules on how data locks are respected: All statements ignore data locks owned its own transaction. SELECT query statements ignores data locks owned by any transactions. INSERT, UPDATE, and DELETE statements in a READ COMMITTED transaction will wai... 2019-08-08, 2502🔥, 0💬

IN - Testing Value in a Value List in SQL Server
What To Test Value Lists with the IN Operator in SQL Server Transact-SQL? Sometimes you want to test a given value against a list of values. You can do this in a loop with the regular "equal" operator. But you can also use the special comparison operator IN to get it done with the following syntaxes... 2017-01-21, 2502🔥, 0💬

Using Values from Other Tables in UPDATE Statements in SQL Server
How To Use Values from Other Tables in UPDATE Statements in SQL Server? If you want to update values in one table with values from another table, you can use a subquery as an expression in the SET clause. The subquery should return only one row for each row in the update table that matches the WHERE... 2016-11-02, 2502🔥, 0💬

SQL Server FAQs - PHP ODBC Functions - Managing Tables and Data Rows
A collection of 14 FAQs on using PHP ODBC functions to connect to manage tables and data rows. Clear explanations and tutorial exercises are provided on creating tables; inserting multiple data rows; updating and deleting data rows; searching data from multiple tables; looping through result sets; w... 2024-06-03, 2501🔥, 0💬

Assign Data from a Deleted Row to Variables in Oracle
How To Assign Data of the Deleted Row to Variables in Oracle? If a DELETE statement is deleting a single row, you can assign column values of the deleted row to variables by using the RETURNING clause, which an extension of DELETE statements for PL/SQL. The tutorial script shows you how to do this: ... 2018-09-13, 2501🔥, 0💬

CURRENT_ROLE() - Current Role of Logged-In User
How to obtain the current role of the logged-in user using the CURRENT_ROLE() function? CURRENT_ROLE() is a MySQL built-in function that returns the current role of the logged-in user. For example: SELECT CURRENT_ROLE(); -- +----------------+ -- | CURRENT_ROLE() | -- +----------------+ -- | NONE | -... 2024-07-15, 2500🔥, 0💬

Show All Background Sessions in the Database in Oracle
How To Get a List of All Background Sessions in the Database in Oracle? If you don't like to use a SELECT statement to get a list of all background sessions in the current database, you can use the Reports view to do this as shown in the following tutorial example. You need to connect to the server ... 2019-01-26, 2500🔥, 0💬

Retrieve Field Values from RECORD Variables in Oracle
How To Retrieve Values from Data Fields in RECORD Variables in Oracle? If a variable is a RECORD variable with data fields assigned values, you can retrieve those values out of its data fields by using fields names prefixed with variable name as "variable.field_name". Here is a sample script showing... 2018-09-01, 2500🔥, 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, 2500🔥, 0💬

"OPEN" - Executing the Query of a Cursor in SQL Server
How To Execute the Cursor Queries with "OPEN" Statements in SQL Server Transact-SQL? Once a cursor is declared, you need to execute the query attached to the cursor so that the result set returned from the query can be accessed through the cursor. To execute the cursor query, you should use the OPEN... 2016-10-17, 2499🔥, 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, 2496🔥, 0💬

PHP ODBC - Creating a New Table
PHP ODBC - How To Create a New Table? If you want to create a table in the database connected through a ODBC DSN, you can run the CREATE TABLE SQL statement using the odbc_exec() function, as shown in the following sample script: &lt;?php $con = odbc_connect('FYI_SQL_SERVER', 'sa','FYIcenter');#... 2024-06-03, 2495🔥, 0💬

Providing Default Values to Procedure Parameters in SQL Server
How To Provide Default Values to Stored Procedure Parameters in SQL Server Transact-SQL? If you add a parameter when creating a stored procedure, you can provide a default value so that the execution statement is not required to pass input value to this parameter. To provide a default value to a par... 2016-12-28, 2494🔥, 0💬

What Are User Defined Functions in SQL Server
What Are User Defined Functions in SQL Server Transact-SQL? A user defined function is a collection of Transact-SQL statements that stored in the SQL Server. A user defined function will return data when executed. A user defined function works in the same way as a system function. It can be used as ... 2016-12-28, 2493🔥, 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, 2493🔥, 0💬

IN - Testing Values Returned by a Subquery in SQL Server
How To Test Values Returned by a Subquery with the IN Operator in SQL Server Transact-SQL? Normally, the comparison operator IN is used against a list of specified values as in the format of: "test_value IN (value_1, value_2, ..., value_n)". But you can also replace the list of values by a subquery ... 2017-01-21, 2492🔥, 0💬

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General MySQL Oracle SQL Server