General MySQL Oracle SQL Server

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What Is a Dead Lock in MySQL
What Is a Dead Lock in MySQL? A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram: (transaction 1) (transaction 2) update row X to create lock 1 update row Y to create lock 2 update row X (blo... 2017-04-28, 2756🔥, 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, 2755🔥, 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, 2750🔥, 0💬

Quoting Text Values in MySQL
How To Quote Text Values in SQL Statements in MySQL? Text values in SQL statements should be quoted with single quotes ('). If the text value contains a single quote ('), it should be protected by replacing it with two single quotes (''). In SQL language syntax, two single quotes represents one sing... 2017-06-28, 2749🔥, 0💬

Show All Tables in a Database in MySQL
How To Get a List of All Tables in a Database in MySQL? If you want to see the table you have just created, you can use the "SHOW TABLES" command to get a list of all tables in database. The tutorial script gives you a good example: mysql&gt; SHOW TABLES; +---------------+ | Tables_in_fyi | +---... 2018-03-10, 2748🔥, 0💬

What Is MySQL Server Daemon - mysqld in MySQL
What Is the MySQL Server Daemon - mysqld in MySQL? "mysqld" is MySQL server daemon program which runs quietly in background on your computer system. Invoking "mysqld" will start the MySQL server on your system. Terminating "mysqld" will shutdown the MySQL server. Here is a tutorial example of invoki... 2017-12-09, 2748🔥, 0💬

NAME_CONST() - PS Thread ID of Given Connect
How to provide a column name for a constant in a SELECT statement using the NAME_CONST() function? NAME_CONST(con) is a MySQL built-in function that provides a column name for a constant in a SELECT statement. For example: SELECT NAME_CONST('domain', 'dba.fyicenter.com'); -- +-------------------+ --... 2025-01-07, 2747🔥, 0💬

Add a New Column to an Existing Table in MySQL
How To Add a New Column to an Existing Table in MySQL? If you have an existing table with existing data rows, and want to add a new column to that table, you can use the "ALTER TABLE ... ADD COLUMN" statement. The tutorial script below shows you a good example: mysql&gt; ALTER TABLE tip ADD COLU... 2018-03-04, 2747🔥, 0💬

What Is View in MySQL
What Is View in MySQL? A view is a logical table defined by a query statement.   ⇒ What Is Join in MySQL ⇐ What Is Index in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2744🔥, 0💬

Failed to Create a Database in MySQL
What Happens If You Do Not Have Privileges to Create Database in MySQL? If your MySQL server is provided by your Internet service company, your user account will most likely have no privilege to create new databases on the server. In that case, your CREATE DATABASE statement will fail. Here is an ex... 2017-11-11, 2743🔥, 0💬

Returning Top 5 Rows in MySQL
How To Return Top 5 Rows in MySQL? If you want the query to return only the first 5 rows, you can use the LIMIT clause, which takes one parameter as the maximum number of rows to return. The following statement returns the first 5 rows from the fyi_links: mysql&gt; SELECT id, url, counts, tag FR... 2017-12-21, 2742🔥, 0💬

Adding a New User Account in MySQL
How To Add a New User Account in MySQL? If you want to add a new user account, you can connect to the server as "root" and use the "CREATE USER ..." command. The command syntax for create a new user account with a specified user name and password is: CREATE USER userName IDENTIFIED BY 'passwordStrin... 2017-09-08, 2733🔥, 0💬

Deleting an Existing Row from a Table in MySQL
How To Delete an Existing Row from a Table in MySQL? If you want to delete an existing row from a table, you can use the DELETE statement with a WHERE clause to identify that row. Here is good sample of DELETE statements: mysql&gt; INSERT INTO fyi_links (url, id) VALUES ('www.myspace.com', 301);... 2018-01-08, 2729🔥, 0💬

Creating New Tables with SELECT Statements in MySQL
How To Create a New Table by Selecting Rows from Another Table in MySQL? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the "CREATE TABLE ... SELECT" statement. The tutorial script below gives you a good... 2018-03-04, 2727🔥, 0💬

Using Table Alias Names in MySQL
How To Define and Use Table Alias Names in MySQL? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names as shown in the following select statement: mysql&gt; SELECT l.id, l.url, r.comment FROM fyi_links l INNER JOIN fyi_rates ... 2017-12-31, 2726🔥, 0💬

Database Basics and Terminologies in MySQL
Where to find answers to frequently asked questions on Database Basics and Terminologies in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Database Basics and Terminologies in MySQL to help you review your knowledge. A short answer is prov... 2017-07-21, 2724🔥, 0💬

What Is NULL Value in MySQL
What Are NULL Values in MySQL? NULL is a special value that represents no value. Here are basic rules about NULL values: NULL presents no value. NULL is not the same as an empty string ''. NULL is not the same as a zero value 0. NULL can be used as any data type. NULL should not be used in any compa... 2018-03-28, 2722🔥, 0💬

Create a Table for Transaction Testing in MySQL
How To Create a Table for Transaction Testing in MySQL? If you want to learn transaction management, you should create a table with the InnoDB storage engine. The default storage engine MyISAM does not support the transaction concept. The tutorial exercise below shows you a good example of creating ... 2016-10-17, 2721🔥, 0💬

Sorting Query Output in MySQL
How To Sort the Query Output in MySQL? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The simplest sort expression is column name who's values will be sorted by. The following select statement returns rows sorted by the values in the "counts... 2017-11-02, 2720🔥, 0💬

Update Column Values on Multiple Rows in MySQL
How To Update Column Values on Multiple Rows in MySQL? If the WHERE clause in an UPDATE 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: mysql&gt; UPDATE fyi_lin... 2018-01-13, 2719🔥, 0💬

Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to u... 2017-09-17, 2718🔥, 0💬

Inserting a New Row into a Table in MySQL
How To Insert a New Row into a Table in MySQL? To insert a new row into a table, you should use the INSERT INTO statement with values specified for all columns as shown in the following example: mysql&gt; INSERT INTO fyi_links VALUES (101, 'dev.fyicenter.com', NULL, 0, '2006-04-30'); Query OK, 1... 2018-01-16, 2716🔥, 0💬

Turn on Error Logs in MySQL
How To Turn on Error Logs in MySQL? If you want MySQL to write critical errors into a log file, you can use the "--log-error=fileName" option at the "mysqld" command line. The tutorial exercise below shows you a good example on how to use this option: &gt;cd \mysql\bin &gt;mkdir \mysql\logs ... 2017-11-29, 2710🔥, 0💬

Quoting Date and Time Values in MySQL
How To Quote Date and Time Values in SQL Statements in MySQL? If you want to provide date and time values in a SQL statement, you should write them in the format of "yyyy-mm-dd hh:mm:ss", and quoted with single quotes ('). The tutorial exercise below shows you two INSERT statements. The first one us... 2017-06-23, 2710🔥, 0💬

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General MySQL Oracle SQL Server