General MySQL Oracle SQL Server

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Deleting All Rows in a Table in MySQL
How To Delete All Rows in a Table in MySQL? If you want to delete all rows from a table, you have two options: Use the DELETE statement with no WHERE clause. Use the TRUNCATE TABLE statement. The TRUNCATE statement is more efficient the DELETE statement. The tutorial exercise shows you a good exampl... 2018-01-08, 2874🔥, 0💬

Start Oracle SQL Developer in Oracle
How To Start Oracle SQL Developer in Oracle? To start Oracle SQL Developer, go to \sqldeveloper and click sqldeveloper.exe. The Oracle SQL Developer window shows up. Your copy of Oracle SQL Developer is running now. There will nothing under the Connections icon, because you haven't defined any conne... 2019-02-05, 2873🔥, 0💬

Start Oracle SQL Developer in Oracle
How To Start Oracle SQL Developer in Oracle? To start Oracle SQL Developer, go to \sqldeveloper and click sqldeveloper.exe. The Oracle SQL Developer window shows up. Your copy of Oracle SQL Developer is running now. There will nothing under the Connections icon, because you haven't defined any conne... 2019-02-05, 2873🔥, 0💬

Create a New Table in Your Schema in Oracle
How To Create a New Table in Your Schema in Oracle? If you want to create a new table in your own schema, you can log into the server with your account, and use the CREATE TABLE statement. The following script shows you how to create a table: &gt;.\bin\sqlplus /nolog SQL&gt; connect HR/fyice... 2019-06-01, 2872🔥, 0💬

Use DML Statements in PL/SQL in Oracle
Can DML Statements Be Used in PL/SQL in Oracle? Yes, you can run almost any DML statements in PL/SQL directly. To manipulate Oracle database data you can include INSERT, UPDATE, and DELETE statements, directly in PL/SQL programs, without any special notation, as shown in the following sample code: (... 2018-10-13, 2872🔥, 0💬

What Is NULL Value in MySQL
What Are NULL Values in MySQL? NULL is a special value that represents no value. Here are basic rules about NULL values: NULL presents no value. NULL is not the same as an empty string ''. NULL is not the same as a zero value 0. NULL can be used as any data type. NULL should not be used in any compa... 2018-03-28, 2872🔥, 0💬

Attributes of the Implicit Cursor in Oracle
How To Use Attributes of the Implicit Cursor in Oracle? Right after executing a DML statement, you retrieve any attribute of the implicit cursor by using SQL%attribute_name, as shown in the following tutorial exercise: CREATE TABLE student (id NUMBER(5) PRIMARY KEY, first_name VARCHAR(80) NOT NULL, ... 2018-02-01, 2870🔥, 0💬

Update Column Values on Multiple Rows in MySQL
How To Update Column Values on Multiple Rows in MySQL? If the WHERE clause in an UPDATE matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example: mysql&gt; UPDATE fyi_lin... 2018-01-13, 2870🔥, 0💬

Sorting Query Output in MySQL
How To Sort the Query Output in MySQL? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The simplest sort expression is column name who's values will be sorted by. The following select statement returns rows sorted by the values in the "counts... 2017-11-02, 2870🔥, 0💬

Experiments of Data Locks in Oracle
How To Experiment a Data Lock in Oracle? If you want to have some experience with data locks, you can create two windows running two SQL*Plus sessions. In session 1, you can run a UPDATE statements to create a data lock. Before committing session 2, switch to session 2, and run a UPDATE statements o... 2019-08-08, 2869🔥, 0💬

Export Data with Field Delimiters in Oracle
How To Export Data with a Field Delimiter in Oracle? The previous exercise allows you to export data with fixed field lengths. If you want export data with variable field lengths and field delimiters, you can concatenate your fields with an expression in the SELECT clause as shown in the tutorial ex... 2018-06-27, 2867🔥, 0💬

Creating New Tables with SELECT Statements in MySQL
How To Create a New Table by Selecting Rows from Another Table in MySQL? Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the "CREATE TABLE ... SELECT" statement. The tutorial script below gives you a good... 2018-03-04, 2866🔥, 0💬

Types of Cursors Supported in PL/SQL in Oracle
How Many Types of Cursors Supported in PL/SQL in Oracle? PL/SQL supports two types of cursors: The implicit cursor - A single default cursor that automatically connects to the last DML statement executed. Explicit cursors - User defined cursors with specific DML statements and execution statuses.   ... 2018-02-01, 2866🔥, 0💬

Turn on Error Logs in MySQL
How To Turn on Error Logs in MySQL? If you want MySQL to write critical errors into a log file, you can use the "--log-error=fileName" option at the "mysqld" command line. The tutorial exercise below shows you a good example on how to use this option: &gt;cd \mysql\bin &gt;mkdir \mysql\logs ... 2017-11-29, 2866🔥, 0💬

Defining and Using Table Alias Names in SQL Server
How To Define and Use Table Alias Names in SQL Server? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names. To define an alias for a table name, just enter the alias name right after the original table name in the FROM clause as... 2016-10-30, 2866🔥, 0💬

Show All User Accounts in the Database in Oracle
How To Get a List of All User Accounts in the Database in Oracle? If you don't like to use a SELECT statement to get a list of all user accounts in the current database, you can use the Reports view to do this as shown in the following tutorial example. You need to connect to the server as SYSTEM to... 2019-01-26, 2865🔥, 0💬

Quoting Date and Time Values in MySQL
How To Quote Date and Time Values in SQL Statements in MySQL? If you want to provide date and time values in a SQL statement, you should write them in the format of "yyyy-mm-dd hh:mm:ss", and quoted with single quotes ('). The tutorial exercise below shows you two INSERT statements. The first one us... 2017-06-23, 2865🔥, 0💬

Define an Anonymous Block in Oracle
How To Define an Anonymous Block in Oracle? An anonymous block must have an execution part, which is a group of other PL/SQL statements enclosed in the BEGIN ... END statement. Here is a script on how to define a simple anonymous block with SQL*Plus: SQL&gt; set serveroutput on; SQL&gt; begi... 2018-10-30, 2864🔥, 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, 2863🔥, 0💬

Using SELECT Statements and GROUP BY Clauses in SQL Server
Where to find answers to frequently asked questions on Using SELECT Statements and GROUP BY Clauses in SQL Server? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on Using SELECT Statements and GROUP BY Clauses in SQL Server. Clear answers are provid... 2016-10-26, 2863🔥, 0💬

Types of Tables Supported by Oracle in Oracle
How Many Types of Tables Supported by Oracle in Oracle? Oracle supports 4 types of tables based on how data is organized in storage: Ordinary (heap-organized) table - This is the basic, general purpose type of table. Its data is stored as an unordered collection (heap) Clustered table - A clustered ... 2019-06-01, 2862🔥, 0💬

Update a Table Row with a RECORD in Oracle
How To Update a Table Row with a RECORD in Oracle? If you have a RECORD variable with data fields matching a table structure, you can update a row in this table with this RECORD variable using the UPDATE ... SET ROW statement as shown in the sample script below: CREATE TABLE emp_temp AS SELECT * FRO... 2018-08-14, 2862🔥, 0💬

What Is Variable in SQL Server Transact-SQL
What is a variable in SQL Server Transact-SQL? A variable in Transact-SQL is a symbolic name representing a memory storage that holds a piece of data. A variable has the following the components: 1. Variable name - A symbolic name to represent the variable. Variable names in Transact-SQL must starts... 2017-04-22, 2862🔥, 0💬

Rollback the Current Transaction in Oracle
How To Rollback the Current Transaction in Oracle? If you have used some DML statements updated some data objects, you find a problem with those updates, and you don't want those updates to be permanently recorded in the database, you can use the ROLLBACK statement. It will remove all the database c... 2019-09-04, 2861🔥, 0💬

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General MySQL Oracle SQL Server