General MySQL Oracle SQL Server

<< < … 40 41 42 43 44 45 46 47 48 49 50 … > >>   ∑:1360  Sort:Date

Using Subqueries with the EXISTS Operators in SQL Server
How To Use Subqueries with the EXISTS Operators in SQL Server? A subquery can be used with the EXISTS operator as "EXISTS (subquery)", which returns true if the subquery returns one or more rows. The following statement is a good example of "EXISTS (subquery)". It returns rows from fyi_links table t... 2016-10-29, 2586🔥, 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, 2584🔥, 0💬

Apply Filtering Criteria at Group Level in Oracle
How To Apply Filtering Criteria at Group Level in Oracle? If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. The following script gives you a good HAVING example: SQL&gt; SELECT dep... 2019-11-21, 2583🔥, 0💬

Data File of BDB Storage Engine in MySQL
Where Table Data Is Stored by the BDB Storage Engine in MySQL? By default, MySQL provides \mysql\data directory for all storage engines to store table data. Under \mysql\data directory, the BDB storage engine will create one file for each table to store table data and index data. If a new table is c... 2017-08-13, 2583🔥, 0💬

"DROP DATABASE" - Deleting Databases in SQL Server
How to delete a database in SQL Server? If you created a database incorrectly, or you have a database that is not needed any more, you can delete it with the "DROP DATABASE" statement with this syntax: DROP DATABASE database_name For example, execute this statement: DROP DATABASE FyiCenterData GO Th... 2016-11-24, 2582🔥, 0💬

Define a RECORD Variable for a Table Row in Oracle
How To Define a RECORD Variable to Store a Table Row in Oracle? If you have a table, and want to define a RECORD variable to store all the data elements of a row from that table, you can use table_name%ROWTYPE to define the RECORD variable as shown in the following sample script: CREATE TABLE studen... 2018-08-14, 2578🔥, 0💬

Query with an Inner Join in MySQL
How To Write a Query with an Inner Join in MySQL? 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 fyi.r... 2017-12-31, 2578🔥, 0💬

NULL Values Involved in Bitwise Operations in SQL Server
What Happens If NULL Values Are Involved in Bitwise Operations in SQL Server Transact-SQL? If NULL values are involved in bitwise operations, the result will be binary NULL values. The following tutorial script shows you some good examples: SELECT 1 | NULL; GO ----------- NULL SELECT 707 &amp; N... 2017-02-03, 2578🔥, 0💬

What Is a Dead Lock in Oracle
What Is a Dead Lock in Oracle? A dead lock is phenomenon happens between two transactions with each of them holding a lock that blocks the other transaction as shown in the following diagram: (transaction 1) (transaction 2) update row X to create lock 1 update row Y to create lock 2 update row X (bl... 2019-08-08, 2577🔥, 0💬

List All Tables with "mysql" Command in MySQL
How To Show All Tables with "mysql" in MySQL? If you want to see all the tables in a database, you run the non-SQL command "SHOW TABLES" at the "mysql" prompt. See the following tutorial exercise for example: &gt;cd \mysql\bin &gt;mysql -u root test Welcome to the MySQL monitor. Commands end... 2018-02-28, 2574🔥, 0💬

ntwdblib.dll - SQL Server Client Library DLL
What Is Wrong with SQL Server Client Library DLL, ntwdblib.dll? The second requirement to access SQL Server with PHP scripts is the SQL Server Client Library DLL, ntwdblib.dll. The good news is that the Windows binary version of PHP 5.2.3 has ntwdblib.dll included in the PHP home directory. But the ... 2024-04-14, 2573🔥, 0💬

What Do You Think about PL/SQL in Oracle
What Do You Think about PL/SQL in Oracle? After following through the tutorials in the FAQ collection, you probably agree that PL/SQL is indeed a general purpose database programming language. PL/SQL is a natural extension of SQL. It is very useful for DBA to automate specific administration tasks o... 2019-02-18, 2573🔥, 0💬

Invoke Original Export/Import Utiities in Oracle
How To Invoke Original Export/Import Utilities in Oracle? If you really want to run the original export import utilities, you can still go to "bin" directory of the Oracle server path and run the "exp" or "imp" command. The tutorial exercise below tells you how to run the export and import utilities... 2016-10-15, 2573🔥, 0💬

Turn on Binary Logs in MySQL
How To Turn on Binary Logs in MySQL? If you want MySQL to write binary logs to a file, you can use the "--log-bin=fileBaseName" 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 &gt... 2017-11-29, 2571🔥, 0💬

Sort the Query Output in Oracle
How To Sort the Query Output in Oracle? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The following select statement returns rows sorted by the values in the "manager_id" column: SQL&gt; SELECT * FROM departments ORDER BY manager_id; DE... 2019-12-19, 2570🔥, 0💬

Getting "Connection failed" Error on ODBC DSN Creation
Why Am I Getting Errors When Creating a New ODBC DSN? Continue from the previous tutorial. After clicking Next on the SQL login information screen, ODBC manager will try to connect to the SQL Server with the login information you provided. After a period of waiting time, you may get error message bo... 2024-08-06, 2569🔥, 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, 2569🔥, 0💬

CREATE INDEX - Adding an Index on an Existing Table in SQL Server
How To Create an Index on an Existing Table in SQL Server? If you want to an index on an existing table, you can use the CREATE INDEX statement in a simple syntax: CREATE INDEX index_name ON table_name (column_name) The tutorial exercise below shows you how to add an index for the "in" column of the... 2016-11-15, 2569🔥, 0💬

Subtracting a DATETIME Value from Another DATETIME Value in SQL Server
Can a DATETIME Value Be Subtracted from Another DATETIME Value in SQL Server Transact-SQL? Can a datetime value be subtracted from another datetime value? The answer is yes. The subtract operation can be performed by the subtract operator (-) as: datetime1 - datetime2: Returning a DATETIME value cal... 2017-02-20, 2566🔥, 0💬

EXISTS - Testing Subquery Results in SQL Server
How To Test Subquery Results with the EXISTS Operator in SQL Server Transact-SQL? EXISTS is a special operator used to test subquery results. EXISTS can be used in two ways: EXISTS (SELECT ...) -- Returns TRUE if the specified subquery has one or more rows returned. NOT EXISTS (SELECT ...) -- Return... 2017-01-21, 2566🔥, 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, 2566🔥, 0💬

Define a Specific RECORD Type in Oracle
How To Define a Specific RECORD Type in Oracle? If you want to define a specific RECORD type, you need to use the TYPE ... IS RECORD statement in the declaration part of any procedure or function. The following example script defines a RECORD type called STUDENT: CREATE OR REPLACE PROCEDURE HELLO AS... 2018-09-01, 2565🔥, 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, 2565🔥, 0💬

Types of Execution Flow Control Statements in Oracle
What Are the Execution Control Statements in Oracle? PL/SQL supports three groups of execution control statements: IF Statements - Conditionally executes a block of statements. CASE Statements - Selectively executes a block of statements. LOOP Statements - Repeatedly executes a block of statements. ... 2018-11-17, 2564🔥, 0💬

<< < … 40 41 42 43 44 45 46 47 48 49 50 … > >>   ∑:1360  Sort:Date

General MySQL Oracle SQL Server