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What Are Indexes in SQL Server
What Are Indexes in SQL Server? An index is a secondary database object associated with a table to improve the retrieval performance of rows from that table. An index can be defined for a single column or multiple columns of a given table. If an index is defined on a single column of a table, the in...
2016-11-15, 4429🔥, 0💬

Increment Dates by 1 in Oracle
How To Increment Dates by 1 in Oracle? If you have a date, and you want to increment it by 1. You can do this by adding the date with a date interval. You can also do this by adding the number 1 directly on the date. The tutorial example below shows you how to adding numbers to dates, and take date ...
2020-03-15, 4416🔥, 0💬

What Is a Table Index in Oracle
What Is a Table Index in Oracle? Index is an optional structure associated with a table that allow SQL statements to execute more quickly against a table. Just as the index in this manual helps you locate information faster than if there were no index, an Oracle Database index provides a faster acce...
2020-11-22, 4414🔥, 0💬

Requirements for SQL*Plus Connection in Oracle
What Information Is Needed to Connect SQL*Plus an Oracle Server in Oracle? If you want to connect your SQL*Plus session to an Oracle server, you need to know the following information about this server: The network hostname, or IP address, of the Oracle server. The network port number where the Orac...
2020-08-25, 4404🔥, 0💬

Generate Query Output in HTML Format in Oracle
How To Generate Query Output in HTML Format in Oracle? If you want your query output to be generated in HTML format, you can use the "SET MARKUP HTML ON" to turn on the HTML feature. The following tutorial exercise gives you a good example: SQL&gt; connect HR/retneciyf SQL&gt; SET MARKUP HTM...
2020-07-15, 4404🔥, 0💬

Get System Date and Time in SQL Server Transact-SQL
How to get system date and time in SQL Server Transact-SQL? I want a list of functions for getting current system date and time. Here is a comparison of all functions that you can use to get the current date and time from the data base server system: Function Return type Precision ------------------...
2017-02-25, 4390🔥, 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, 4375🔥, 0💬

Output Spooling in SQL*Plus in Oracle
What Is Output Spooling in SQL*Plus in Oracle? The output spooling a nice feature of the command-line SQL*Plus tool. If the spooling feature is turned on, SQL*Plus will send a carbon copy of the everything on your screen to a specified local file. Output spooling is used mostly for quick dump of dat...
2020-07-15, 4372🔥, 0💬

Entering Date and Time Values in SQL Server
How To Enter Date and Time values in SQL Server Transact-SQL? Transact-SQL does not support date and time literals. If you want to enter date and time values, you have to use character string literals and rely implicit casting rules to convert them into date and time values. When casting character s...
2017-04-15, 4361🔥, 0💬

UPDATE with Subquery Returning No Rows in MySQL
What Happens If the UPDATE Subquery Returns No Rows in MySQL? 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, MySQL will provide a NULL value to the SET clause. The tutorial exercise below shows you a good exampl...
2018-01-08, 4360🔥, 0💬

What Is a Static Data Dictionary in Oracle
What Is a Static Data Dictionary in Oracle? Data dictionary tables are not directly accessible, but you can access information in them through data dictionary views. To list the data dictionary views available to you, query the view DICTIONARY. Many data dictionary tables have three corresponding vi...
2020-10-26, 4358🔥, 0💬

How To Count Duplicated Values in a Column? in SQL Server
How To Count Duplicated Values in a Column in SQL Server? 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....
2016-10-25, 4349🔥, 0💬

Change Transaction Isolation Level in MySQL
How To View and Change the Current Transaction Isolation Level in MySQL? If you want to view or change the current transaction isolation level, you can use the following commands: SELECT @@TX_ISOLATION FROM DUAL; -- Viewing the current transaction isolation level. SET TRANSACTION ISOLATION LEVEL lev...
2017-08-08, 4345🔥, 0💬

Calculating the Difference between Two Time Values in MySQL
How To Calculate the Difference between Two Time Values in MySQL? If you have two time values, and you want to know the time difference between them, you can use the TIMEDIFF(time1, time2) function as shown below: SELECT TIMEDIFF(TIME('19:26:50'), TIME('09:26:50')) FROM DUAL; 10:00:00 SELECT TIMEDIF...
2017-12-26, 4343🔥, 0💬

Overflow and Rounding on NUMERIC Values in SQL Server Transact-SQL
How Extra Digits Are Handled with NUMERIC Data Type Literals in SQL Server Transact-SQL? Exact numeric data types defined with NUMERIC(p,s) has two limits defined by two parameters: p (precision) and s (scale): Maximum number of digits of the integer part (digits before the decimal point) is defined...
2017-04-19, 4340🔥, 0💬

Import One Table back from a Dump File in Oracle
How To Import One Table Back from a Dump File in Oracle? If you only want to import one table back to the database, you can use a dump file that was created by full export, schema export or a table export. The following tutorial exercise shows you how to import the "fyi_links" table from a dump file...
2016-10-15, 4338🔥, 0💬

OFFLINE - Taking a database offline in SQL Server
How to set a database state to OFFLINE in SQL Server? If you want to move database physical files, you should take the database offline by using the "ALTER DATABASE" statement with the following syntax: ALTER DATABASE database_name SET OFFLINE The following tutorial example will bring "FyiCenterComD...
2016-11-20, 4337🔥, 0💬

Error: Single-Row Subquery Returns More Than One Row in Oracle
What Happens If the UPDATE Subquery Returns Multiple Rows in Oracle? If a subquery is used in a UPDATE statement, it must return exactly one row for each row in the update table that matches the WHERE clause. If it returns multiple rows, Oracle server will give you an error message. To test this out...
2020-01-21, 4329🔥, 0💬

Introduction to Oracle Database 10g Express Edition
Where to find answers to frequently asked questions on Oracle Database 10g Express Edition? I want to learn how to install Oracle database. Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Oracle Database 10g Express Edition with installation instr...
2020-05-15, 4314🔥, 0💬

Main Features of SQL*Plus in Oracle
What Is SQL*Plus in Oracle? SQL*Plus is an interactive and batch query tool that is installed with every Oracle Database Server or Client installation. It has a command-line user interface, a Windows Graphical User Interface (GUI) and the iSQL*Plus web-based user interface. SQL*Plus has its own comm...
2020-08-25, 4309🔥, 0💬

What Is a Database Table in Oracle
What Is a Database Table in Oracle? A database table is a basic unit of data logical storage in an Oracle database. Data is stored in rows and columns. You define a table with a table name, such as employees, and a set of columns. You give each column a column name, such as employee_id, last_name, a...
2020-11-22, 4305🔥, 0💬

What Is Microsoft SQL Server in SQL Server
What is Microsoft SQL Server in SQL Server? Microsoft SQL Server is a relational database management system (RDBMS) developed by Microsoft. It runs on Windows systems and uses Transact-SQL as the query language. Microsoft SQL Server release history: 1993 - SQL Server 4.21 for Windows NT 1995 - SQL S...
2016-12-08, 4302🔥, 0💬

Understanding SQL Transaction Management in Oracle
Where to find answers to frequently asked questions on SQL Transaction Management in Oracle? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SQL Transaction Management in Oracle. Clear answers are provided with tutorial exercises on starting and e...
2019-09-16, 4295🔥, 0💬

ALTER INDEX - Rename an Index in Oracle
How To Rename an Index in Oracle? Let's say you have an existing index, and you don't like its name anymore for some reason, you can rename it with the ALTER INDEX ... RENAME TO statement. Here is an example script on how to rename an index: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name...
2020-02-20, 4287🔥, 0💬

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