by Dinesh Thakur Category: SQL Commands

It is important to note that the INNER JOIN only returns data where a match is found. While using the inner join we have seen that if there exists certain records in one table. Which doesn't have corresponding values in the second table then those rows will not be selected.

 
by Dinesh Thakur Category: SQL Commands

The result of a left outer join (or simply left join) for table A and B always contains records of the "left" table (A), even if the join-condition does not find any matching record in the "right" table (B). This means that if the ON clause matches 0 (zero) records in B, the join will still return a row in the result-but with NULL in each column from B.

 
by Dinesh Thakur Category: SQL Commands

To retrieve the Employee name, job, salary, deptno, dname from EMP, DEPT table. It will return all information regarding the employees and the department information. This is Full Outer Join's Example.



 
by Dinesh Thakur Category: SQL Commands

A cross join, or product provides the foundation upon which all types of inner joins operate. A cross join returns the Cartesian product of the sets of records from the two joined tables. Thus, it equates to an inner join where the join-condition always evaluates to true or join-condition is absent in statement. This command is introduced for Oracle9i. If A and B are two sets, then the cross join is written as A x B.

 
by Dinesh Thakur Category: SQL Commands

When the user fires a SELECT statement to search for a particular record, the oracle engine must first locate the table on the hard disk. The Oracle engine reads the information and locates the starting location of a table's record on the current storage media.



 
by Dinesh Thakur Category: SQL Commands

The SQL DROP INDEX statement is the SQL command that removes an entire SQL index. You may drop an index permanently when it is no longer useful or temporarily. If the index is harming or not helping performance it could be dropped.

 
by Dinesh Thakur Category: SQL Functions

SQL COUNT is the aggregate arithmetic function. COUNT allows us to COUNT number of row that matches specified criteria. This function returns the number of rows in the query. The COUNT function will only count those records in which the field in the brackets is NOT NULL. The SQL COUNT function is easy to use.

 
by Dinesh Thakur Category: SQL Functions

All of the aforementioned functions relate to specific ways to manipulate character, date/time, or numeric datatypes. But you may need to convert data from one datatype to another or convert NULL values to something meaningful.

 
by Dinesh Thakur Category: SQL Functions

 The ROUND function allows you to round any numeric value. The general format is:

ROUND (NumericValue, DecimalPlaces)
 
by Dinesh Thakur Category: SQL Functions

The simplest of the date/time functions is one that returns the current date and time. In Microsoft SQL Server, the function is named GETDATE. This function has no arguments. It merely returns the current date and time. For example:

 
by Dinesh Thakur Category: SQL Functions

The simplest of the date/time functions is one that returns the current date and time. In Microsoft SQL Server, the function is named GETDATE. This function has no arguments. It merely returns the current date and time. For example:

 
by Dinesh Thakur Category: SQL Functions

The simplest of the date/time functions is one that returns the current date and time. In Microsoft SQL Server, the function is named GETDATE. This function has no arguments. It merely returns the current date and time. For example:

 
by Dinesh Thakur Category: SQL Functions

The DECODE function can be thought of as an inline IF statement. DECODE takes three or more expressions as arguments. Each expression can be a column, a literal, a function, or even a subquery. Let's look at a simple example using DECODE:

 
by Dinesh Thakur Category: SQL Functions

The NVL and NVL2 functions allow you to test an expression to see whether it is NULL. If an expression is NULL, you can return an alternate, non-NULL value, to use in its place. Since any of the expressions in a DECODE statement can be NULL, the NVL and NVL2 functions are actually specialized versions of DECODE. The following example uses NVL2 to produce the same results as the DECODE:

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.