General MySQL Oracle SQL Server

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Query with a Full Outer Join in MySQL
How To Write a Query with a Full Outer Join in MySQL? There is no way to do full outer join in MySQL. It does not support this feature at the current MySQL release.   ⇒ Inner Join with the WHERE Clause in MySQL ⇐ Query with a Right Outer Join in MySQL ⇑ SELECT Statements with JOIN and Subqueries in... 2017-09-28, 2190🔥, 0💬

Use "IN" Parameters in Oracle
How To Use "IN" Parameter Properly in Oracle? Here are the rules about IN parameters: A formal IN parameter acts like constant. It can not be assigned with new values. An actual IN parameter can take a value or a variable. An actual IN parameter is passed by reference to the specified value or the v... 2018-10-19, 2189🔥, 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, 2188🔥, 0💬

Read Consistency in Oracle in Oracle
How Does Oracle Handle Read Consistency in Oracle? Oracle supports two options for you on how to maintain read consistency: READ WRITE (the default option), also called statement-level read consistency. READ ONLY, also called transaction-level read consistency.   ⇒ What Is a READ WRITE Transaction i... 2019-08-23, 2187🔥, 0💬

Create a Table Interactively in Oracle
How To Create a Table Interactively in Oracle? If you don't want to use SQL statements to create a new table, you use SQL Developer to create one interactively. Follow the steps below to create a new table called: TIP Right-click on the Tables in the object tree area. Select Create TABLE. Create Tab... 2018-10-08, 2187🔥, 0💬

Load Data from External Tables in Oracle
How To Load Data from External Tables to Regular Tables in Oracle? Once you have your data entered in a text file, and an external table defined to this text file, you can easily load data from this text file to a regular table. The following tutorial exercise shows you how to load data from the tex... 2016-10-15, 2187🔥, 0💬

What Do You Think about PL/SQL in Oracle
What Do You Think about PL/SQL in Oracle? After following through the tutorials in the FAQ collection, you probably agree that PL/SQL is indeed a general purpose database programming language. PL/SQL is a natural extension of SQL. It is very useful for DBA to automate specific administration tasks o... 2019-02-18, 2186🔥, 0💬

Duplicate Key Error on Primary Key Columns in SQL Server
What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server? If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow dupl... 2016-11-02, 2185🔥, 0💬

Create an Index for a Given Table in MySQL
How To Create an Index for a Given Table in MySQL? If you have a table with a lots of rows, and you know that one of the columns will be used often as a search criteria, you can add an index for that column to improve the search performance. To add an index, you can use the "CREATE INDEX" statement ... 2018-02-14, 2184🔥, 0💬

Data Types Supported in PL/SQL in Oracle
How Many Data Types Are Supported in Oracle? PL/SQL supports two groups of data types: SQL Data Types - All data types used for table columns. PL/SQL Special Data Types - Like BOOLEAN or PLS_INTEGER. The script below shows some data type examples: SQL&gt; set serveroutput on; SQL&gt; DECLARE... 2019-03-20, 2183🔥, 0💬

Run the Anonymous Block Again in Oracle
How To Run the Anonymous Block Again in Oracle? If you have an anonymous block defined in your session, you can run it any time by using the "/" command as shown in the following script: SQL&gt; set serveroutput on; SQL&gt; begin 2 dbms_output.put_line('This is a PL/SQL FAQ.'); 3 end; 4 / Th... 2018-10-30, 2183🔥, 0💬

What Are Group Functions in Oracle
What Are Group Functions in Oracle? 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... 2019-12-19, 2182🔥, 0💬

What Is SQL Standard in MySQL
What Is SQL Standard in MySQL? SQL, SEQUEL (Structured English Query Language), is a language for RDBMS (Relational Database Management Systems). SQL was developed by IBM Corporation. SQL became an ANSI standard, called SQL-87, in 1986. ISO made a major revision, called SQL-92, in 1992. The latest r... 2018-04-21, 2182🔥, 0💬

Creating and Managing Triggers in SQL Server
Where to find answers to frequently asked questions on Creating and Managing Triggers in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Creating and Managing Triggers in SQL Server. Clear explanations and tutorial exercises are provid... 2016-10-25, 2182🔥, 0💬

NULL Values Involved in Arithmetic Operations in SQL Server
What Happens If NULL Values Are Involved in Arithmetic Operations in SQL Server Transact-SQL? If NULL values are involved in arithmetic operations, the result will be numeric NULL values. The following tutorial script shows you some good examples: SELECT 7+NULL; GO ----------- NULL SELECT 10.02*NULL... 2017-02-05, 2181🔥, 0💬

Show the Current Transaction Mode in MySQL
How To Find Out the Current Transaction Mode in MySQL? If you are not sure about your current transaction mode, you can use the "SELECT @@AUTOCOMMIT FROM DUAL" statement to find out as shown in the following tutorial exercise: &gt;\mysql\bin\mysql -u dev -piyf fyi mysql&gt; SELECT @@AUTOCOMM... 2016-10-17, 2181🔥, 0💬

Enabling TCP/IP Protocol on a SQL Server
How To Enable TCP/IP Protocol on a SQL Server? By default, the TCP/IP protocol is turned off when a SQL Server is installed to reduce security risk. But if you want applications to connect and access the SQL Server, you need to enable the TCP/IP protocol on the server by following this tutorial: 1. ... 2024-07-25, 2180🔥, 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, 2180🔥, 0💬

CREATE INDEX - Adding an Index on an Existing Table in SQL Server
How To Create an Index on an Existing Table in SQL Server? If you want to an index on an existing table, you can use the CREATE INDEX statement in a simple syntax: CREATE INDEX index_name ON table_name (column_name) The tutorial exercise below shows you how to add an index for the "in" column of the... 2016-11-15, 2180🔥, 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, 2180🔥, 0💬

Managing Databases and Physical Files in SQL Server
Where to find answers to frequently asked questions on Managing Databases and Physical Files in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Managing Databases and Physical Files in SQL Server. Clear answers are provided with tutori... 2016-11-24, 2179🔥, 0💬

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, 2178🔥, 0💬

Creating a New Table in MySQL
How To Create a New Table in MySQL? If you want to create a table, you can run the CREATE TABLE statement as shown in the following sample script: &lt;?php include "mysql_connection.php"; $sql = "CREATE TABLE fyi_links (" . " id INTEGER NOT NULL" . ", url VARCHAR(80) NOT NULL" . ", notes VARCHAR... 2017-10-08, 2178🔥, 0💬

"INSTEAD OF" - Overriding DML Statements with Triggers in SQL Server
How To Override DML Statements with Triggers in SQL Server? Sometime, you may want to implement some business logics in a DML trigger to cancel the DML statement. For example, you may want to check the new email address format provided by the UPDATE statement. If the email address is invalid, you to... 2016-10-22, 2178🔥, 0💬

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General MySQL Oracle SQL Server