General MySQL Oracle SQL Server

<< < … 37 38 39 40 41 42 43 44 45 46 47 … > >>   ∑:1349  Sort:Date

Deleting a Table That Is Used by a View in SQL Server
What Happens If You Delete a Table That Is Used by a View in SQL Server? Assuming that you have a table which is used by a view, and you try to delete that table. SQL Server will let you delete the table without any trouble. But that view will become invalid. The tutorial exercise below shows you wh... 2016-11-04, 2299🔥, 0💬

What Is Binary Log File in MySQL
What Is Binary Log File in MySQL? MySQL server binary log file plays an important role in restoring database changes to the server. Main features on binary log files are: Binary logs can be turned on by "--log-bin=fileBaseName" option on "mysqld". Binary logs only records statements that are changin... 2017-11-29, 2298🔥, 0💬

Retrieving Execution Error Message in MySQL
How To Get MySQL Statement Execution Errors in MySQL? When you execute a MySQL statement with mysql_query(), and the statement failed, mysql_query() will return the Boolean value FALSE. This is good enough to tell that there is something wrong with that statement. But if you want to know more about ... 2017-10-23, 2298🔥, 0💬

Getting Month and Weekday Names from DATATIME Values in SQL Server
How To Get Month and Weekday Names from DATETIME Values in SQL Server Transact-SQL? In DATETIME values, the month part and weekday part have names. You can use the DATENAME() function to get the month name and weekday name from a DATETIME value in the following format: DATENAME(datepart, date) retur... 2017-02-14, 2298🔥, 0💬

SELECT Statements with JOIN and Subqueries in MySQL
Where to find answers to frequently asked questions on SELECT Statements with JOIN and Subqueries in MySQL? Here is a list of frequently asked questions and their answers compiled by FYIcenter.com DBA team on SELECT Statements with JOIN and Subqueries in MySQL. Clear answers are provided with tutori... 2017-12-31, 2297🔥, 0💬

Execute SQL Statements in MySQL
How To Execute a SQL Statement in MySQL? You can run any types of SQL statements through the mysql_query() function. It takes the SQL statement as a string and returns different types of data depending on the SQL statement type and execution status: Returning FALSE, if the execution failed. Returnin... 2017-10-23, 2297🔥, 0💬

"CREATE TRIGGER" - Creating a DML Trigger in SQL Server
How To Create a DML Trigger using CREATE TRIGGER Statements in SQL Server? A DML trigger is a trigger declared to handle a DML event, which occurs when an INSERT, UPDATE or DELETE statement is executed. If you want to create a DML trigger, you should use the "CREATE TRIGGER" statement in the followi... 2016-10-25, 2297🔥, 0💬

Creating an Index for Multiple Columns in SQL Server
How To Create an Index for Multiple Columns in SQL Server? An index for multiple columns works similarly to a sorting process on multiple columns. If an index is defined for two columns, the index key is composed by values from those two columns. A multi-column index will be used to speed up the sea... 2016-11-13, 2296🔥, 0💬

Primary Key - Default Indexes of Tables in SQL Server
Is the PRIMARY KEY Column of a Table an Index in SQL Server? If you define a primary key on a table, an index for the primary key column will be created by default. The tutorial exercise below shows you the index created as part of the primary key column of "fyi_links": USE FyiCenterData; GO -- Drop... 2016-11-13, 2296🔥, 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, 2296🔥, 0💬

Sorting Query Output in Descending Order in SQL Server
How To Sort Query Output in Descending Order in SQL Server? If you want to sort a column in descending order, you can specify the DESC keyword in the ORDER BY clause. The following SELECT statement first sorts the "tag" in descending order, then sorts the "counts" in ascending order: SELECT tag, cou... 2016-10-26, 2296🔥, 0💬

Load Data from External Tables in Oracle
How To Load Data from External Tables to Regular Tables in Oracle? Once you have your data entered in a text file, and an external table defined to this text file, you can easily load data from this text file to a regular table. The following tutorial exercise shows you how to load data from the tex... 2016-10-15, 2296🔥, 0💬

What Is Foreign Key in MySQL
What Is Foreign Key in MySQL? A foreign key is a single column or multiple columns defined to have values that can be mapped to a primary key in another table.   ⇒ What Is Index in MySQL ⇐ What Is Primary key in MySQL ⇑ Database Basics and Terminologies in MySQL ⇑⇑ MySQL Database Tutorials 2017-07-07, 2295🔥, 0💬

Create a Test Table for DML Testing in Oracle
How To Create a Testing Table in Oracle? If you want to practice DML statements, you should create a testing table as shown in the script below: CREATE TABLE fyi_links (id NUMBER(4) PRIMARY KEY, url VARCHAR2(80) NOT NULL, notes VARCHAR2(1024), counts NUMBER, created DATE DEFAULT (sysdate)); Table cr... 2020-02-07, 2294🔥, 0💬

Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to u... 2017-09-17, 2294🔥, 0💬

Duplicate Key Error on Primary Key Columns in SQL Server
What Happens If You Insert a Duplicate Key for the Primary Key Column in SQL Server? If your table has a primary key column, and you are trying to insert a new row with duplicate key value on the primary key column, you will get an error. The reason is simple - Primary key column does not allow dupl... 2016-11-02, 2294🔥, 0💬

Group Functions with Non-group Selections in MySQL
Can Group Functions Be Mixed with Non-group Selection Fields in MySQL? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of invalid S... 2017-10-16, 2293🔥, 0💬

Updating Values with UPDATE Statements in SQL Server
How To Update Values in a Table with UPDATE Statements in SQL Server? If you want to update some values in one row or multiple rows in a table, you can use the UPDATE statement. The tutorial script below shows a good example: SELECT * FROM fyi_links WHERE id = 101 GO id url notes counts created 101 ... 2016-11-02, 2293🔥, 0💬

Data Types Supported in PL/SQL in Oracle
How Many Data Types Are Supported in Oracle? PL/SQL supports two groups of data types: SQL Data Types - All data types used for table columns. PL/SQL Special Data Types - Like BOOLEAN or PLS_INTEGER. The script below shows some data type examples: SQL&gt; set serveroutput on; SQL&gt; DECLARE... 2019-03-20, 2292🔥, 0💬

Use Existing Column Values in SET Clause in Oracle
How To Use Existing Values in UPDATE Statements in Oracle? If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by columns in the expressions. The tutorial exercise bel... 2020-01-21, 2291🔥, 0💬

Cursor Variable Easier to Use than Cursor in Oracle
Why Cursor Variables Are Easier to Use than Cursors in Oracle? Cursor variables are easier to use than cursors because: Cursor variables are easier to define. No need to give a specific query statement. Cursor variables are easier to open. You can specify the query dynamically at the time of open. C... 2018-06-27, 2291🔥, 0💬

What Is a Database in SQL Server
What is a database in SQL Server? A database is a logical container that contains a set of related database objects: Tables - Storages of structured data. Views - Queries to present data from tables. Indexes - Sorting indexes to speed up searches. Stored Procedures - Predefined SQL program units. Us... 2016-11-24, 2291🔥, 0💬

Enter a New Row Interactively in Oracle
How To Enter a New Row into a Table Interactively in Oracle? If you don't like to use the INSERT statement to enter a new row into a table, you can use the object view to enter it interactively. Follow the steps below to enter new row into table TIP: Double-click on the table name TIP. Click the Dat... 2018-10-08, 2289🔥, 0💬

Loop through the Implicit Cursor in Oracle
How To Loop through Data Rows in the Implicit Curosr in Oracle? You use the FOR ... IN ... LOOP statement to loop through data rows in the implicit cursor as the following syntax: FOR row IN dml_statement LOOP (statement block with row.field) END LOOP; Here "row" is a local RECORD type variable with... 2018-07-22, 2289🔥, 0💬

<< < … 37 38 39 40 41 42 43 44 45 46 47 … > >>   ∑:1349  Sort:Date

General MySQL Oracle SQL Server