General MySQL Oracle SQL Server

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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, 2959🔥, 0💬

"ALTER TABLE ... ADD" - Adding New Columns to Existing Tables in SQL Server
How To Add a New Column to an Existing Table with "ALTER TABLE ... ADD" in SQL Server? If you have an existing table with existing data rows, and want to add a new column to that table, you can use the "ALTER TABLE ... ADD" statement. The tutorial script below shows you a good example: ALTER TABLE t... 2016-11-17, 2959🔥, 0💬

JSON_OVERLAPS() - Checking JSON Overlaps
How to check if two JSON values have overlaps using the JSON_OVERLAPS() function? JSON_OVERLAPS(json1, json2) is a MySQL built-in function that detects overlaps of two JSON values using the following rules: If both arguments are objects, overlap means they have at least one key-value pair in common.... 2024-12-18, 2954🔥, 0💬

Transaction Roll Back when Session Killed in MySQL
What Happens to the Current Transaction If the Session Is Killed in MySQL? If a session is killed by the DBA, the current transaction in that session will be rolled back and ended. All the database changes made in the current transaction will be removed. This is called an implicit rollback when sess... 2017-08-03, 2954🔥, 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, 2953🔥, 0💬

Differences of DECIMAL and FLOAT in SQL Server
What Are the Differences between DECIMAL and FLOAT in SQL Server Transact-SQL? DECIMAL and FLOAT are both used to store numerical values. But they have the following main differences: DECIMAL(p,s) stores values with the decimal point fixed at the position of s (scale) digits from the right. The tota... 2026-02-12, 2950🔥, 1💬

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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, 2948🔥, 0💬

Delete a Column in an Existing Table in Oracle
How To Delete a Column in an Existing Table in Oracle? If you have an existing column in a table and you need that column any more, you can delete it with ALTER TABLE ... DROP COLUMN statement. Here is an example SQL script: SQL&gt; CREATE TABLE emp_dept_90 2 AS SELECT * FROM employees WHERE dep... 2019-05-25, 2946🔥, 0💬

Character Strings and Binary Strings in SQL Server Transact-SQL
Where to find answers to frequently asked questions on Character Strings and Binary Strings in SQL Server Transact-SQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Character Strings and Binary Strings in SQL Server Transact-SQL. Clear answers ... 2017-03-11, 2946🔥, 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, 2944🔥, 0💬

What Is RollBack in MySQL
What Is Rollback in MySQL? Rollback is a way to terminate a transaction with all database changes not saving to the database server.   ⇒ MySQL Database Tutorials ⇐ What Is Commit in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2016-10-16, 2943🔥, 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, 2941🔥, 0💬

MySQL Functions for Encryption and Compression
Where to find reference information and tutorials on MySQL database functions for Encryption and Compression? I want to know how to use COMPRESS(), ENCRYPT() and other related functions. Here is a collection of reference information and tutorials on MySQL database functions for Encryption and Compre... 2025-03-12, 2934🔥, 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, 2933🔥, 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, 2933🔥, 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, 2932🔥, 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, 2931🔥, 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, 2930🔥, 0💬

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, 2930🔥, 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, 2928🔥, 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, 2928🔥, 0💬

Calculating the Difference between Two Dates in MySQL
How To Calculate the Difference between Two Dates in MySQL? If you have two dates, and you want to know how many days between them, you can use the DATEDIFF(date1, date2) function as shown below: SELECT DATEDIFF(DATE('1997-02-28'), DATE('1997-03-01')) FROM DUAL; -1   ⇒ Calculating the Difference bet... 2017-12-26, 2927🔥, 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, 2923🔥, 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, 2921🔥, 0💬

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General MySQL Oracle SQL Server