General MySQL Oracle SQL Server

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Show Dropped Tables in Recycle Bin in Oracle
How To View the Dropped Tables in Your Recycle Bin in Oracle? You can look what's in your recycle bin through the predefined view called RECYCLEBIN. You can use the SELECT statement to list the dropped tables as shown in the following script: SQL&gt; connect HR/fyicenter Connected. SQL&gt; C... 2019-05-14, 3032🔥, 0💬

Using Group Functions in the SELECT Clause in MySQL
How To Use Group Functions in the SELECT Clause in MySQL? 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 3 values cal... 2018-01-06, 3032🔥, 0💬

Dropped Tables with Indexes in Oracle
What Happens to Indexes If You Drop a Table in Oracle? If you drop a table, what happens to its indexes? The answer is that if a table is dropped, all its indexes will be dropped too. Try the following script to see yourself: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT... 2019-04-22, 3029🔥, 0💬

DML (Data Manipulation Language_Statements in SQL Server
What Are DML (Data Manipulation Language) Statements in SQL Server? 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. For example "INSERT INTO fyi_links VALUES (101,... 2016-11-03, 3028🔥, 0💬

CONVERT/CAST Function in SQL Server Transact-SQL
How to convert value from one data type to another in SQL Server Transact-SQL? How to use the CONVERT function or the CAST function? In Transact-SQL, you can use CONVERT statements to convert values from one data type to another, in the syntax of: CONVERT(data_type, value[, style]) In this syntax, "... 2017-04-01, 3027🔥, 0💬

"FETCH" - Fetching the Next Row from a Cursor in SQL Server
How To Fetch the Next Row from a Cursor with a "FETCH" Statement in SQL Server Transact-SQL? When the result set is ready in a cursor, you can use a FETCH statement to retrieve one row from the result set in the same format as a SELECT statement. The FETCH statement has the following formats: FETCH ... 2016-10-17, 3027🔥, 0💬

MySQL Server Features in MySQL
What Is MySQL in MySQL? MySQL is an open source database management system developed by MySQL AB, http://www.mysql.com. MySQL has the following main features: Works on many different platforms. APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl are available. Fully multi-threaded using ... 2018-06-12, 3025🔥, 0💬

What Is ODBC in Oracle
What Is Open Database Communication (ODBC) in Oracle? ODBC, Open Database Communication, a standard API (application program interface) developed by Microsoft for Windows applications to communicate with database management systems. Oracle offers ODBC drivers to allow Windows applications to connect... 2020-05-15, 3024🔥, 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, 3017🔥, 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, 3017🔥, 0💬

Create a Stored Procedure in Oracle
How To Create a Stored Procedure in Oracle? A stored procedure is a procedure with a specified name and stored into the current database. If you want to create a stored procedure, you can use the CREATE PROCEDURE statement. The example script below creates a stored procedure: SQL&gt; CREATE PROC... 2018-11-11, 3016🔥, 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, 3015🔥, 0💬

Delete Multiple Rows from a Table in Oracle
How To Delete Multiple Rows from a Table in Oracle? You can delete multiple rows from a table in the same way as deleting a single row, except that the WHERE clause will match multiple rows. The tutorial exercise below deletes 3 rows from the fyi_links table: SELECT * FROM fyi_links WHERE id &gt... 2020-01-04, 3014🔥, 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, 3010🔥, 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, 3010🔥, 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, 3009🔥, 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, 3009🔥, 0💬

Add a New Column to an Existing Table with a Default Value in Oracle
How To Add a New Column to an Existing Table with a Default Value in Oracle? If you want to add a new column to an existing table, and insert a default value in this column on all existing data rows, you can use the ALTER TABLE ... ADD statement with the DEFAULT clause. Here is an example script: SQ... 2019-05-25, 3008🔥, 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, 3007🔥, 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, 3005🔥, 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, 3004🔥, 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, 3004🔥, 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, 3002🔥, 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, 2997🔥, 0💬

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General MySQL Oracle SQL Server