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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, 2975🔥, 0💬

What Is a Subquery in Oracle
What Is a Subquery in Oracle? A subquery is a SELECT statement used as part of the selection criteria of the main SELECT statement. The subquery specified in the WHERE clause will be evaluated repeated on each row of the selection base table. The output of the subquery will be used in the final eval...
2019-09-27, 2974🔥, 0💬

Default Collation in SQL Server Transact-SQL
How To Find Out What Is the Default Collation in SQL Server Transact-SQL? The default collation of a database comes from the server if you are not using the COLLATE clause in the CREATE DATABASE statement. If you are not using the COLLATE clause for character string column, it will use the default c...
2017-05-13, 2974🔥, 0💬

Managing Oracle Database Tables
Where to find answers to frequently asked questions on Managing Oracle Database Tables? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Managing Oracle Database Tables. Clear answers are provided together with tutorial exercises to help beginners ...
2019-06-11, 2973🔥, 0💬

Variable Names Collide with Column Names in Oracle
What Happens If Variable Names Collide with Table/Column Names in Oracle? When a variable name collides with a column name, PL/SQL will use it as the variable if it is used where variable is allowed; It will be used as the column, if it is used where variable is not allowed but column is allowed. He...
2018-09-24, 2970🔥, 0💬

Privilege to Create Views in Oracle
What Privilege Is Needed for a User to Create Views in Oracle? To be able to create views in a user's own schema, the user needs to have the CREATE VIEW privilege, or the CREATE ANY VIEW privilege, which is more powerful, and allows the user to create views in other user's schema. The following tuto...
2019-06-29, 2969🔥, 0💬

SCHEMA() - Synonym for DATABASE()
What's the difference between SCHEMA() and DATABASE() functions? SCHEMA() is a synonym for the DATABASE() function. Related MySQL functions: DATABASE() - Name of Current Database SCHEMA() - Synonym for DATABASE()   ⇒ SESSION_USER() - Synonym for USER() ⇐ ROW_COUNT() - Affected Rows from Last DML St...
2025-02-16, 2965🔥, 0💬

Show All Columns of an Existing Table in MySQL
How To Get a List of Columns in an Existing Table in MySQL? If you have an existing table, but you don't remember what are the columns used in the table, you can use the "SHOW COLUMNS FROM tableName" command to get a list of all columns of the specified table. You can also use the "DESCRIBE tableNam...
2018-03-10, 2965🔥, 0💬

ONLINE/OFFLINE - Database States in SQL Server
What are database states in SQL Server? A database is always in one specific state. For example, these states include ONLINE, OFFLINE, or SUSPECT. To verify the current state of a database, select the state_desc column in the sys.databases catalog view. The following table defines the database state...
2016-11-20, 2964🔥, 0💬

Error: Cannot Identify/Lock Data File in Oracle
What Happens If You Lost a Data File in Oracle? After you shutting down an Oracle database, you accidently deleted a data file from the operating system. If you try to start the database again you will get error when Oracle tries to open the database after mounting the database. The following tutori...
2019-04-09, 2963🔥, 0💬

Rules on Arithmetic Operations in SQL Server
What Are Arithmetic Operators in SQL Server Transact-SQL? An arithmetic operator performs an arithmetic operation on two expressions of numeric data types. SQL Server supports 5 arithmetic operators: + (Add): Addition - (Subtract): Subtraction * (Multiply): Multiplication / (Divide): Division % (Mod...
2017-04-01, 2963🔥, 0💬

"INNER JOIN ... ON" - Writing Queries with Inner Joins in SQL Server
How To Write a Query with an Inner Join in SQL Server? If you want to query from two tables with an inner join, you can use the INNER JOIN ... ON clause in the FROM clause. The tutorial exercise below creates another testing table and returns output with an inner join from two tables: fyi_links and ...
2016-10-30, 2958🔥, 0💬

Tables Using MEMORY Storage Engine in MySQL
How To Create a New Table Using the MEMORY Storage Engine in MySQL? MEMORY storage engine stores table data in computer system memory. This is good for creating temporary tables. MEMORY is not the default storage engine. You need to specify "ENGINE = MEMORY" at the end of the "CREATE TABLE" statemen...
2017-08-08, 2957🔥, 0💬

Differences between CHAR and VARCHAR in Oracle
What Are the Differences between CHAR and VARCHAR2 in Oracle? The main differences between CHAR and VARCHAR2 are: CHAR stores values in fixed lengths. Values are padded with space characters to match the specified length. VARCHAR2 stores values in variable lengths. Values are not padded with any cha...
2020-04-25, 2954🔥, 0💬

Differences between NUMBER and BINARY_FLOAT in Oracle
What Are the Differences between NUMBER and BINARY_FLOAT in Oracle? The main differences between NUMBER and BINARY_FLOAT are: NUMBER stores values as fixed-point numbers using 1 to 22 bytes. BINARY_FLOAT stores values as single precision floating-point numbers.   ⇒ Differences between DATE and TIMES...
2020-04-25, 2952🔥, 0💬

Numeric Literals in Oracle
How To Write Numeric Literals in Oracle? Numeric literals can coded as shown in the following samples: SELECT 255 FROM DUAL -- An integer 255 SELECT -6.34 FROM DUAL -- A regular number -6.34 SELECT 2.14F FROM DUAL -- A single-precision floating point 2.14 SELECT -0.5D FROM DUAL -- A double-precision...
2020-04-14, 2952🔥, 0💬

Concatenating Two Binary Strings in SQL Server
How To Concatenate Two Binary Strings Together in SQL Server Transact-SQL? SQL Server 2005 allows to concatenate two binary strings into a single string with the (+) operator. The following tutorial exercise shows you some binary string concatenation examples: -- Concatenating two binary string lite...
2017-03-07, 2952🔥, 0💬

Using SELECT Statements on Views in SQL Server
Can SELECT Statements Be Used on Views in SQL Server? Select (query) statements can be 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: CREATE VIEW myLinks AS SELECT * FROM fyi_links WHERE url LIKE '%fyi%' G...
2016-10-26, 2950🔥, 0💬

Convert Times to Character Strings in Oracle
How To Convert Times to Character Strings in Oracle? You can convert dates to characters using the TO_CHAR() function as shown in the following examples: SELECT TO_CHAR(SYSDATE, 'HH:MI:SS') FROM DUAL; 04:49:49 SELECT TO_CHAR(SYSDATE, 'HH24:MI:SS.FF') FROM DUAL; -- Error: SYSDATE has no fractional se...
2019-12-02, 2949🔥, 0💬

Use SYS Account to Connect to the Server in Oracle
How To Connect to the Server with User Account: SYS in Oracle? SYS is a very special user account. It has been associated with the highest privilege call SYSDBA. Normally, you should not connect to the server with SYS. But if you want to use it, you need to use a special connect command: &gt;cd ...
2019-07-21, 2949🔥, 0💬

What Is "mysqlcheck" Command in MySQL
What Is "mysqlcheck" in MySQL? "mysqlcheck" is a command-line interface for administrators to check and repair tables. Here are some sample commands supported by "mysqlcheck": "mysqlcheck databaseName tableName" - Checks the specified table in the specified database. "mysqlcheck databaseName" - Chec...
2018-02-28, 2947🔥, 0💬

Date and Time Interval Literals in Oracle
How To Write Date and Time Interval Literals in Oracle? Date and time interval literals can coded as shown in the following samples: SELECT DATE '2002-10-03' + INTERVAL '123-2' YEAR(3) TO MONTH FROM DUAL -- 123 years and 2 months is added to 2002-10-03 03-DEC-25 SELECT DATE '2002-10-03' + INTERVAL '...
2020-03-25, 2942🔥, 0💬

Date and Time Functions Supported by SQL Server 2005 in SQL Server
What Are the Date and Time Functions Supported by SQL Server 2005 in SQL Server Transact-SQL? SQL Server 2005 supports n character string functions: DATEADD(datepart, number, date) - Returning the same date and time value with one part added with the "number". DATEDIFF(datepart, startdate, enddate) ...
2017-02-20, 2942🔥, 0💬

SQL Server Connection Protocols
What connection protocols are supported by SQL Server? SQL Server supports the following connection protocols: 1. TCP/IP (Transmission Control Protocol/Internet Protocol) - This is the most commonly used protocols to connect to SQL Server databases. It allow client tools or application programs on a...
2024-08-14, 2939🔥, 0💬

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