What Is a Join

Q

What Is a Join?

✍: fyicenter.com

A

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 returns rows from two or more tables based upon a relationship other than the equality condition in the WHERE clause.
Outer Join combines two or more tables returning those rows from one table that have no direct match in the other table.
Self Join joins a table to itself as though it were two separate tables.

2007-04-15, 4740👍, 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, 4741👍, 0💬

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What Are Date Functions? Date Functions are ADD_MONTHS, LAST_DAY, NEXT_DAY, MONTHS_BETWEEN and SYSDATE. 2007-04-15, 4650👍, 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, 4645👍, 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, 4585👍, 0💬

What Is NVL
What Is NVL? NVL is a function lets you substitute a value when a null value is encountered. 2007-04-15, 4546👍, 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, 4536👍, 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, 4528👍, 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, 4500👍, 0💬

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