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Superkey in SQL – Definition And Example

In SQL, a superkey refers to a set of columns present in a table which contains no two rows sharing a similar combination of values. Therefore, each row in the table has its own unique superkey. Moreover, a superkey can simply be a single column as well. Example of A Superkey Suppose we have a […]

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Tips For Tuning SQL Indexes For Efficient Performance

The indexes are used for making queries run more rapidly by decreasing the time taken to look up data. However, the substitute for that enhanced performance is that indexes also take up space, and there should be some repairs done on the indexes to make sure that they keep on running efficiently. Here are a […]

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What Is The Difference Between Parameterized Queries And Prepared Statements?

The prepared statements and parameterized queries both are the same thing. However, the prepared statement is a commonly used term in programming, there is no particular difference between the two terms. They both are the features of management systems in the database which act as templates to execute the SQL. The actual passed values in the […]

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In SQL, What’s The Difference Between The Having Clause And The Group By Statement?

In structured query language(SQL) to group the columns of a table in addition to perform some aggregate functions like sum, difference, minimum, maximum etc, and when we want to compare the aggregate functions having clause is used with group by statement. Read on the example below to understand it better. Example: We have a table […]

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In SQL, What’s The Difference Between A Full Join And An Inner Join?

Before we move on to the actual differences between a full join and an inner join, we need to understand what exactly a join is. Joins, as the name suggests, are used to combine data of two different tables into a new temporary table. The resultant table is created on the basis of the column(s) […]

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What Is Referential Integrity

  It is a complex term which is related to data base concepts and ensures that an integral relationship between tables stay consistent. In simple words, if one table possesses a foreign key which is linked to another table, then according to referential integrity you cannot add an additional record to the table if the […]

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What Is The SQL CASE Statement?

The SQL CASE statement is SQL’s way of handling IF-THEN-ELSE logic statements. What are the IF-THEN-ELSE logic statements? They are conditional statements that behave according to the given condition (i.e. if A = B then do something else do something different). You can use the CASE statement to give your SQL query several alternatives for […]

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Difference Between A Derived Table And A Subquery?

There is quite a lot of confusion over derived tables and subqueries because of their similar structures. Most people believe that they are the same thing but it’s not true – there are definite and concrete differences between the two objects. Subqueries: A subquery is essentially a query within a query. It is a SELECT […]

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What Is The Difference Between Correlated Subqueries And Uncorrelated Subqueries?

The meaning of a subquery can be understood from its name – it’s a query within a query. Subquery is also known as a nested query and is used to restrict the search results after they have been filtered from the main query. Subqueries are used with UPDATE, SELECT, DELETE and INSERT statements. Statements of […]

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What Is A Bitmap Index?

So, what is a bitmap index? A bitmap index is a special way of arranging information in a relational database to save time and resources. They have specific use cases so it is not something we will run into constantly. Let me explain why. Bitmap indexes organize information for only one column of data in […]

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