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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, 623👍, 0💬

Assign Names to Query Output Columns in MySQL
How To Name Query Output Columns in MySQL? Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example: mysql&gt; SELECT tag AS Categ...
2017-09-28, 623👍, 0💬

Renaming an Existing Column with Management Studio in SQL Server
How to rename an existing column with SQL Server Management Studio in SQL Server? If you are using SQL Server Management Studio, you can rename almost any data objects through the Object Explorer window. The tutorial example below shows you how to rename a column: 1. Run SQL Server Management Studio...
2016-11-15, 623👍, 0💬

DROP INDEX - Removing Existing Indexes in SQL Server
How To Drop Existing Indexes in SQL Server? For some reason, if you want remove an existing index, you can use the DROP INDEX statement with following syntax: CREATE INDEX table_name.index_name The tutorial exercise below shows you how to remove the index "fyi_links_id": USE FyiCenterData; GO SELECT...
2016-11-15, 623👍, 0💬

Using Group Functions in the ORDER BY Clause in SQL Server
Can Group Functions Be Used in the ORDER BY Clause in SQL Server? If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns the maximum "counts" in each group, determined by a unique combination of tag and ye...
2016-10-25, 623👍, 0💬

Use of SELECT Statements in Views in Oracle
Can SELECT Statements Be Used on Views in Oracle? Select (query) statements can used on views in the same way as tables. The following tutorial exercise helps you creating a view and running a query statement on the view: SQL&gt; CREATE VIEW managed_dept AS SELECT * FROM departments WHERE manage...
2019-12-19, 622👍, 0💬

User Privilege Tables in MySQL
Where Are User Privileges Stored on the Server in MySQL? MySQL server has a system database, which hosts a number of system tables to system related information like user privileges. Depending on the scope levels, granted user privileges are stored in different tables: "mysql.user" - Stores privileg...
2017-12-09, 622👍, 0💬

Adding More Data to the Test Table in MySQL
How To Add More Data to the Testing Table in MySQL? If you want to continue with other tutorial exercises in this FAQ collection, you need to add more data to the testing table. Follow the script below to add a new column and: mysql&gt; ALTER TABLE fyi_links ADD COLUMN tag VARCHAR(8); mysql&...
2017-11-02, 622👍, 0💬

NULL Values Involved in Datetime Operations in SQL Server
What Happens If NULL Values Are Involved in Datetime Operations in SQL Server Transact-SQL? If NULL values are involved in datetime operations, the result will be datetime NULL values. The following tutorial script shows you some good examples: USE FyiCenterData; GO SELECT GETDATE()+NULL; GO -------...
2017-02-05, 622👍, 0💬

Testing Table for DML Statements in SQL Server
How To Create a Testing Table with Test Data in SQL Server? If you want to practice DML statements, like INSERT, UPDATE and DELETE statements, you should create a testing table. The tutorial exercise shows you a good example: CREATE TABLE fyi_links (id INTEGER PRIMARY KEY, url VARCHAR(80) NOT NULL, ...
2016-11-03, 622👍, 0💬

Use Subqueries with the IN Operator in Oracle
How To Use Subqueries with the IN Operator in Oracle? 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 ...
2019-09-27, 621👍, 0💬

Select Rows with WHERE Clause in MySQL
How To Select Some Rows from a Table in MySQL? If you don't want select all rows from a table, you can specify a WHERE clause to tell the query to return only the rows that meets the condition defined in the WHERE clause. The WHERE clause condition is a normal Boolean expression. If any data from ta...
2017-11-02, 621👍, 0💬

"DROP LOGIN" - Deleting a Login Name in SQL Server
How To Delete a Login Name in SQL Server? If you don't want to keep a login name any more, you should delete it by using the "DROP LOGIN" statement as shown in this tutorial example: -- Login with "sa" DROP LOGIN Dba_Login; GO Command(s) completed successfully. -- View login names SELECT name, sid, ...
2016-10-19, 621👍, 0💬

Scope of Local Variables in Oracle
What Is the Scope of a Local Variable in Oracle? The scope of a variable can be described with these rules: A variable is valid within the procedure or function where it is defined. A variable is also valid inside a sub procedure or function defined. If a variable name is collided with another varia...
2018-10-13, 620👍, 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, 619👍, 0💬

Understanding and Managing Indexes in SQL Server
Where to find answers to frequently asked questions on Understanding and Managing Indexes in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Understanding and Managing Indexes in SQL Server. Clear answers are provided with tutorial exe...
2016-11-15, 619👍, 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, 619👍, 0💬

Differences between CHAR and NCHAR in Oracle
What Are the Differences between CHAR and NCHAR in Oracle? Both CHAR and NCHAR are fixed length character data types. But they have the following differences: CHAR's size is specified in bytes by default. NCHAR's size is specified in characters by default. A character could be 1 byte to 4 bytes long...
2020-04-25, 618👍, 0💬

Location of Database Files in SQL Server
Where is my database stored on the hard disk in SQL Server? If a database is created with simple CREATE DATABASE statement, the server will create two database files on the hard disk to store data and configuration information about that data bases: database_name.mdf - SQL Server Database Primary Da...
2016-11-24, 618👍, 0💬

"INSERT INTO" - Inserting a New Row into a Table in SQL Server
How To Insert a New Row into a Table with "INSERT INTO" Statements in SQL Server? To insert a new row into a table, you can use the INSERT INTO statement with values specified for all columns as in the following syntax: INSERT INTO table_name VALUES (list_of_values_of_all columns) Note that the list...
2016-11-03, 618👍, 0💬

Start a New Transaction Explicitly in MySQL
How To Start a New Transaction Explicitly in MySQL? If you are confused on the implicit new transaction rules, you can always start a new transaction with the "START TRANSACTION" command to start a new transaction explicitly. "START TRANSACTION" command works in both "Autocommit On" and "Autocommit ...
2016-10-17, 618👍, 0💬

Create Additional Tablespaces in Oracle
How To Create Additional Tablespaces for an New Database in Oracle? This is Step 8. Creating additional tablespaces can be done by using the CREATE TABLESPACE statement as shown in the following sample script: SQL&gt; CREATE TABLESPACE users 2 DATAFILE '/oraclexe/oradata/FYI/users01 .dbf'SIZE 10...
2019-03-27, 617👍, 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, 617👍, 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, 617👍, 0💬

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