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Sample SELECT Statements
Write some simple SELECT Statements SELECT column_name(s) FROM table_name SELECT DISTINCT column_name(s) FROM table_name SELECT column FROM table WHERE column operator value SELECT column FROM table WHERE column LIKE pattern SELECT column,SUM(column) FROM table GROUP BY column SELECT column,SUM(colu... 2007-04-15, 5135👍, 0💬

Operators used in SELECT statements
Name some operators used in SELECT statements = Equal or != Not equal > Greater than = Greater than or equal <= Less than or equal BETWEEN Between an inclusive range LIKE Search for a pattern 2007-04-15, 5151👍, 0💬

What Are DDL Statements
What are the most important DDL statements in SQL? CREATE TABLE - creates a new database table ALTER TABLE - alters (changes) a database table DROP TABLE - deletes a database table CREATE INDEX - creates an index (search key) DROP INDEX - deletes an index 2007-04-15, 5203👍, 0💬

What Is SQL*Loader
What Is SQL*Loader? SQL*Loader is a product for moving data in external files into tables in an Oracle database. To load data from external files into an Oracle database, two types of input must be provided to SQL*Loader: the data itself and the control file. The control file describes the data to b... 2007-04-15, 5639👍, 0💬

What Is Mutating Table
What Is Mutating Table? Mutating Table is a table that is currently being modified by an Insert, Update or Delete statement. Constraining Table is a table that a triggering statement might need to read either directly for a SQL statement or indirectly for a declarative Referential Integrity constrai... 2007-04-15, 5566👍, 0💬

What Is a Deadlock
What Is a Deadlock? Deadlock is a unique situation in a multi user system that causes two or more users to wait indefinitely for a locked resource. First user needs a resource locked by the second user and the second user needs a resource locked by the first user. To avoid dead locks, avoid using ex... 2007-04-15, 5993👍, 0💬

What Is Integrity?
What Is Integrity? Several points about data integrity: Assures database data and structures reflects all changes made to them in the correct sequence. Locks ensure data integrity and maximum concurrent access to data. Commit statement releases all locks. Types of locks are given below. Data Locks p... 2007-04-15, 5803👍, 0💬

What Is Consistency
What Is Consistency? Consistency : Assures users that the data they are changing or viewing is not changed until the are through with it. 2007-04-15, 5521👍, 0💬

What Is Locking
What Is Locking? Locking are mechanisms intended to prevent destructive interaction between users accessing data. Locks are used to achieve. 2007-04-15, 5213👍, 0💬

What Is a Savepoint
What Is a Savepoint? Savepoint is a point within a particular transaction to which you may rollback without rolling back the entire transaction. 2007-04-15, 5278👍, 0💬

What Is Rollback
What Is Rollback? Rollback causes work in the current transaction to be undone. 2007-04-15, 5402👍, 0💬

What Is Posting
What Is Posting? Posting is an event that writes Inserts, Updates and Deletes in the forms to the database but not committing these transactions to the database. 2007-04-15, 7169👍, 0💬

What Is Commit
What Is Commit? Commit is an event that attempts to make data in the database identical to the data in the form. It involves writing or posting data to the database and committing data to the database. Forms check the validity of the data in fields and records during a commit. Validity check are uni... 2007-04-15, 5224👍, 0💬

What Is a Transaction
What Is a Transaction? Transaction is defined as all changes made to the database between successive commits. 2007-04-15, 5145👍, 0💬

In What Order Different Parts of SQL Statements Are Executed
In What Order Different Parts of SQL Statements Are Executed? Where clause, Group By clause, Having clause, Order By clause and Select. 2007-04-15, 5224👍, 0💬

What Are Data Types Limitations
What Are Data Types Limitations? Max. columns in a table is 255. Max. Char size is 255, Long is 64K and Number is 38 digits. Cannot Query on a long column. Char, Varchar2 Max. size is 2000 and default is 1 byte. Number(p,s) p is precision range 1 to 38, s is scale -84 to 127. Long Character data of ... 2007-04-15, 5220👍, 0💬

What Are Indexes
What Are Indexes? Indexes are optional structures associated with tables used to speed query execution and/or guarantee uniqueness. Create an index if there are frequent retrieval of fewer than 10-15% of the rows in a large table and columns are referenced frequently in the WHERE clause. Implied tra... 2007-04-15, 4999👍, 0💬

What Are Synonyms
What Are Synonyms? Synonyms is the alias name for table, views, sequences and procedures and are created for reasons of Security and Convenience. Two levels are Public - created by DBA and accessible to all the users. Private - Accessible to creator only. Advantages are referencing without specifyin... 2007-04-15, 5078👍, 0💬

What Is a Sequences
What Is a Sequences? Sequences are used for generating sequence numbers without any overhead of locking. Drawback is that after generating a sequence number if the transaction is rolled back, then that sequence number is lost. 2007-04-15, 5102👍, 0💬

That Is a Correlated Subquery
That Is a Correlated Subquery? Correlated Subquery is a subquery that is evaluated once for each row processed by the parent statement. Parent statement can be Select, Update or Delete. Use Correlated Subquery to answer multipart questions whose answer depends on the value in each row processed by p... 2007-04-15, 5125👍, 0💬

What Is a Join
What Is a Join? Join is the form of SELECT command that combines info from two or more tables. Types of Joins are Simple (Equijoin and Non-Equijoin), Outer and Self join. Equijoin returns rows from two or more tables joined together based upon a equality condition in the WHERE clause. Non-Equijoin r... 2007-04-15, 5500👍, 0💬

What Are TTITLE and BTITLE
What Are TTITLE and BTITLE? TTITLE and BTITLE are commands to control report headings & footers. 2007-04-15, 5616👍, 0💬

What Are Group Functions
What Are Group Functions? Group Functions returns results based upon groups of rows rather than one result per row, use group functions. They are AVG, COUNT, MAX, MIN and SUM. 2007-04-15, 5064👍, 0💬

What Are Character Functions
What Are Character Functions? Character Functions are INITCAP, UPPER, LOWER, SUBSTR and LENGTH. Additional functions are GREATEST and LEAST. 2007-04-15, 5252👍, 0💬

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.NET C C++ CSS DBA General HTML Java JavaScript JSP JUnit MySQL Networking Oracle Perl Perl PHP PL/SQL RSS Software QA SQL Server Struts Unix Windows XHTML XML