General MySQL Oracle SQL Server

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Show All User Accounts in the Database in Oracle
How To Get a List of All User Accounts in the Database in Oracle? If you don't like to use a SELECT statement to get a list of all user accounts 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 as SYSTEM to... 2019-01-26, 2355🔥, 0💬

Supported Transaction Isolation Levels in Oracle
What Are Transaction Isolation Levels Supported by Oracle in Oracle? Oracle supports two transaction isolation levels: READ COMMITTED (the default option). If the transaction contains DML that requires row locks held by another transaction, then the DML statement waits until the row locks are releas... 2019-08-19, 2354🔥, 0💬

Use Group Functions in the SELECT Clause in Oracle
How To Use Group Functions in the SELECT Clause in Oracle? If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The following select statement returns 4 values ca... 2019-11-21, 2352🔥, 0💬

Count Number of Rows with SELECT Statements in MySQL
How To Use SELECT Statement to Count Number of Rows in MySQL? If you want to count the number of rows, you can use the COUNT(*) function in the SELECT clause. The following tutorial exercise shows you some good example: mysql&gt; SELECT COUNT(*) FROM fyi_links; +----------+ | COUNT(*) | +-------... 2018-01-06, 2350🔥, 0💬

USER() - Login Name of Current User
How to obtain the login name of the current user using the USER() function? USER() is a MySQL built-in function that returns the login name of the current user. Login name is defined as the combination of user name and the client IP address where you logged in from. For example: SELECT USER(); -- +-... 2025-01-07, 2349🔥, 0💬

Inner Join with the WHERE Clause in MySQL
How To Write an Inner Join with the WHERE Clause in MySQL? If you don't want to use the INNER JOIN ... ON clause to write an inner join, you can put the join condition in the WHERE clause as shown in the following query example: mysql&gt; SELECT l.id, l.url, r.comment FROM fyi_links l, fyi_rates... 2017-09-28, 2349🔥, 0💬

What Is Index in MySQL
What Is Index in MySQL? An index is a single column or multiple columns defined to have values pre-sorted to speed up data retrieval speed.   ⇒ What Is View in MySQL ⇐ What Is Foreign Key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2349🔥, 0💬

Assign a Table Row to RECORD Variable in Oracle
How To Assign a Table Row to a RECORD Variable in Oracle? If you have a table, and want to assign a data row of that table to a RECORD variable, you need to define this RECORD variable to match the table column structure, then use the SELECT ... INTO statement to assign a data row that RECORD variab... 2018-08-14, 2347🔥, 0💬

Report View in SQL Developer in Oracle
What Is the Reports View in Oracle SQL Developer in Oracle? The Reports view lets you browse database information that organized by the server as special views. Information can be browsed include: Database parameters Storage information Session information Cursors Data objects User accounts Security... 2018-10-08, 2346🔥, 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, 2346🔥, 0💬

Define a Variable to Match Column Data Type in Oracle
How To Define a Variable to Match a Table Column Data Type in Oracle? If you have a table, and want to define some variables to have exactly the same data types as some columns in that table, you can use table_name.column_name%TYPE as data types to define those variables. The tutorial sample below s... 2018-08-14, 2346🔥, 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, 2346🔥, 0💬

Define the ID Column as Auto-Incremented in MySQL
How To Define the ID Column as Auto-Incremented in MySQL? Many tables require an ID column to assign a unique ID number for each row in the table. For example, if you have a table to hold forum member profiles, you need an ID number to identify each member. To allow MySQL server to automatically ass... 2017-09-12, 2346🔥, 0💬

Converting Numeric Expressions from One Data Type to Another in SQL Server
How To Convert a Numeric Expression from One Data Type to Another in SQL Server Transact-SQL? There are 4 ways to convert a numeric expression from one data type to another data type: Implicit conversion by arithmetic operations - When arithmetic operations are performed on expressions of different ... 2017-03-27, 2346🔥, 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, 2344🔥, 0💬

Create a Table Index in Oracle
How To Create a Table Index in Oracle? If you have a table with a lots of rows, and you know that one of the columns will be used often a search criteria, you can add an index for that column to in improve the search performance. To add an index, you can use the CREATE INDEX statement as shown in th... 2019-05-01, 2342🔥, 0💬

Invoke Built-in Functions in PL/SQL in Oracle
How To Invoke Built-in Functions in PL/SQL in Oracle? Of course, you can invoke SQL functions in SQL statements. But many SQL functions can also be executed in regular PL/SQL statements, as shown in the following sample script: DECLARE now DATE; id NUMBER; str VARCHAR2(40); BEGIN now := SYSDATE; DBM... 2018-09-13, 2342🔥, 0💬

What Are DML Statements in MySQL
What Are DML Statements in MySQL? DML (Data Manipulation Language) statements are statements to change data values in database tables. The are 3 primary DML statements: INSERT - Inserting new rows into database tables. UPDATE - Updating existing rows in database tables . DELETE - Deleting existing r... 2018-01-24, 2342🔥, 0💬

Index Speeding Up SELECT Statements in SQL Server
Does Index Speed Up SELECT Statements in SQL Server? If you want to see the impact of indexes on SELECT statements, you can run the same SELECT statement on "fyi_links" and "fyi_links_indexed" tables. See the tutorial exercise below: USE FyiCenterData; GO -- Run SELECT on the table without indexes D... 2016-11-13, 2342🔥, 0💬

Using Cursors in SQL Server Transact-SQL
Where to find answers to frequently asked questions on Using Cursors in SQL Server Transact-SQL? I want to loop through rows in a result set. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using Cursors in SQL Server Transact-SQL. Clear explanati... 2016-10-17, 2342🔥, 0💬

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, 2341🔥, 0💬

Transaction Committed when DDL Statement Executed in MySQL
What Happens to the Current Transaction If a DDL Statement Is Executed in MySQL? If a DDL statement is executed, the current transaction will be committed and ended. All the database changes made in the current transaction will become permanent. This is called an implicit commit by a DDL statement. ... 2016-10-17, 2341🔥, 0💬

Entering Character Strings in MySQL
How To Include Character Strings in SQL statements in MySQL? If you want to include character strings in your SQL statements, you need to quote them in one of the following formats: Using single quotes. For example 'FYIcenter.com'. Using double quotes. For example "FYI Center". Using single quotes p... 2018-04-12, 2340🔥, 0💬

CASE - Conditional Expressions in SQL Server
What Are Conditional Expressions in SQL Server Transact-SQL? A conditional expression returns one of the given expressions based a specific condition. SQL Server 2005 offers the CASE operator to present a conditional expression with two syntaxes: 1. CASE with simple conditions CASE test_value WHEN v... 2017-01-29, 2340🔥, 0💬

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General MySQL Oracle SQL Server