General MySQL Oracle SQL Server

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Define an Explicit Cursor in Oracle
How To Define an Explicit Cursor in Oracle? An explicit cursor must be defined in the declaration part of a procedure or function with the CURSOR ... IS statement as shown in the following sample script: DECLARE CURSOR c_list IS SELECT * FROM countries; CURSOR t_list IS SELECT * FROM employees WHERE... 2018-07-22, 2291🔥, 0💬

Adding a New Index to a Large Table in SQL Server
What Happens If You Add a New Index to Large Table in SQL Server? An index can be added when you create a new table. New rows will be indexed as they are inserted into the table. But you can also add a new index to an existing table with the same CREATE INDEX statement. The existing rows will be ind... 2016-11-13, 2291🔥, 0💬

Loop through the Implicit Cursor in Oracle
How To Loop through Data Rows in the Implicit Curosr in Oracle? You use the FOR ... IN ... LOOP statement to loop through data rows in the implicit cursor as the following syntax: FOR row IN dml_statement LOOP (statement block with row.field) END LOOP; Here "row" is a local RECORD type variable with... 2018-07-22, 2290🔥, 0💬

Major Storage Engines Supported in MySQL in MySQL
What Are Storage Engines in MySQL? Storage engines are programs that are integrated into MySQL database management system to manage data tables. MySQL 5.0 supports the following major storage engines: MyISAM Storage Engine - MySQL default storage engine. Based on ISAM database concept. MyISAM is not... 2017-09-12, 2290🔥, 0💬

Enter a New Row Interactively in Oracle
How To Enter a New Row into a Table Interactively in Oracle? If you don't like to use the INSERT statement to enter a new row into a table, you can use the object view to enter it interactively. Follow the steps below to enter new row into table TIP: Double-click on the table name TIP. Click the Dat... 2018-10-08, 2289🔥, 0💬

JSON_TYPE() - Detecting Type of JSON Value
How to detect the type of a JSON (JavaScript Object Notation) value using the JSON_TYPE() function? JSON_TYPE(json) is a MySQL built-in function that returns the data type of a JSON (JavaScript Object Notation) value. For example: SELECT JSON_TYPE('[]'), JSON_TYPE('{}'); -- +-----------------+------... 2025-03-12, 2288🔥, 0💬

Viewing Log File with "mysqlbinlog" in MySQL
How To Use mysqlbinlog to View Binary Logs in MySQL? If you have binary logs turned on, you can use "mysqlbinlog" to view the binary log files. The tutorial exercise below shows you how to view two binary files together: &gt;cd \mysql\bin &gt;mysql -u root -pretneciyf test &gt;mysqlbinlo... 2017-11-29, 2288🔥, 0💬

Sort the Query Output in Oracle
How To Sort the Query Output in Oracle? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The following select statement returns rows sorted by the values in the "manager_id" column: SQL&gt; SELECT * FROM departments ORDER BY manager_id; DE... 2019-12-19, 2287🔥, 0💬

Performing Comparison on Floating Point Numbers in SQL Server
How To Perform Comparison on Floating Point Numbers in SQL Server Transact-SQL? Comparison operations on approximate (floating point) numbers are also easy to understand. Just watch out rounding operations performed during conversions. Here are two examples of floating point number comparisons: -- R... 2017-01-21, 2287🔥, 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, 2285🔥, 0💬

SYSTEM_USER() - Synonym for USER()
What's the difference between SYSTEM_USER() and USER() functions? SYSTEM_USER() is a synonym for the USER() function. Related MySQL functions: USER() - Login Name of Current User SESSION_USER() - Synonym for USER() SYSTEM_USER() - Synonym for USER() CURRENT_USER() - Authentication Name of Current Us... 2025-01-07, 2284🔥, 0💬

SINGLE_USER/MULTI_USER - Database User Access Options in SQL Server
How to set database to be SINGLE_USER in SQL Server? Databases in SQL Server have three user access options: MULTI_USER - All users that have the appropriate permissions to connect to the database are allowed. This is the default. SINGLE_USER - One user at a time is allowed to connect to the databas... 2016-11-20, 2282🔥, 0💬

Pass a Parameter to a Cursor in Oracle
How To Pass a Parameter to a Cursor in Oracle? When you define a cursor, you can set a formal parameter in the cursor. The formal parameter will be replaced by an actual parameter in the OPEN cursor statement. Here is a good example of a cursor with two parameters: CREATE OR REPLACE PROCEDURE FYI_CE... 2018-07-18, 2281🔥, 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, 2281🔥, 0💬

Rebuilding All Indexes on One Table in SQL Server
How To Rebuild All Indexes on a Single Table in SQL Server? If you have several indexes on a single table and want to rebuild all of them, you may use the "ALTER INDEX ALL ON table_name REBUILD" statement as shown in the tutorial exercise below: USE FyiCenterData; GO UPDATE fyi_links_indexed SET url... 2016-11-08, 2280🔥, 0💬

Using Subqueries in the FROM Clause in SQL Server
How To Use Subqueries in the FROM Clause in SQL Server? 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 yo... 2016-10-29, 2279🔥, 0💬

NULL Values Involved in Bitwise Operations in SQL Server
What Happens If NULL Values Are Involved in Bitwise Operations in SQL Server Transact-SQL? If NULL values are involved in bitwise operations, the result will be binary NULL values. The following tutorial script shows you some good examples: SELECT 1 | NULL; GO ----------- NULL SELECT 707 &amp; N... 2017-02-03, 2277🔥, 0💬

"DROP SCHEMA" - Dropping an Existing Schema in SQL Server
How To Drop an Existing Schema in SQL Server? If you want to delete a schema, you need to move all objects out of that schema, then use the "DROP SCHEMA" statement to delete the schema. The tutorial exercise below shows you how to drop schema "fyi": -- Login with "sa" USE FyiCenterData; GO -- Drop f... 2016-10-20, 2277🔥, 0💬

Ways to Create an Oracle Database in Oracle
How To Create an Oracle Database in Oracle? There are two ways to create a new database: Use the Database Configuration Assistant (DBCA) to create a database interactively. Use the CREATE DATABASE statement to create a database manually.   ⇒ Create an Oracle Database Manually in Oracle ⇐ Creating N... 2019-04-09, 2274🔥, 0💬

Counting Duplicated Values in a Column in MySQL
How To Count Duplicated Values in a Column in MySQL? If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAVING clause as shown in the following example. It ret... 2017-10-16, 2274🔥, 0💬

Data File of BDB Storage Engine in MySQL
Where Table Data Is Stored by the BDB Storage Engine in MySQL? By default, MySQL provides \mysql\data directory for all storage engines to store table data. Under \mysql\data directory, the BDB storage engine will create one file for each table to store table data and index data. If a new table is c... 2017-08-13, 2274🔥, 0💬

Performing Comparison on Character Strings in SQL Server
How To Perform Comparison on Character Strings in SQL Server Transact-SQL? Comparison operations on character strings are performed based on the associated collation. Each collation defines rules on how characters are ordered, how character cases and accents are treated, etc. The tutorial exercise b... 2017-01-21, 2274🔥, 0💬

"CREATE USER" - Creating a User Name in a Database in SQL Server
How To Create a User Name in a Database in SQL Server? User names are security principals at the database level. If you want to allow a login name to access a specific database, you need to create a user name in that database and link it to the login name. Creating a user name can be done by using t... 2016-10-19, 2274🔥, 0💬

Shutdown MySQL Server Properly in MySQL
How To Properly Shutdown MySQL Server Daemon mysqld in MySQL? The proper way to shutdown your MySQL server is to the use "mysqladmin shutdown" command. Other ways to shutdown your server include: Enter "mysqladmin -u root -ppassowrd shutdown" command with options in a command window. Use Windows Tas... 2017-12-04, 2273🔥, 0💬

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General MySQL Oracle SQL Server