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Difference Between Prepared Statements And Parameterized Queries

Both prepared statements and parameterized queries are exactly the same thing. Basically, the word ‘prepared statement’ is most frequently used; however, there is no difference between these two terms. Prepared statements and parameterized queries are database management system’s characteristics that actually act as templates in which the execution of SQL occurs. The parameters are the […]

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In SQL, What Is Three-Valued (Ternary) Logic?

The answer of this question can be best explained with an example. Just suppose we have the following SQL table having the columns printerrModel and modelNumber:   Computer {   modelNumber CHAR(20) NOT NULL, printerModelCHAR(10),   }   Now assume that the table stores entries for all the ‘makes’ of printers and PC’s – and […]

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What Is A Full Table Scan In Databases?

A full table scan, scans one by one all the rows present in a table for finding the data that a query is searching for. Apparently, this results in very slow SQL queries when you have a table having multiple rows. Now you can even imagine that how performance-rigorous a complete table scan would be […]

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What Is The Concurrent Update Problem In Databases?

Multiple sessions of databases are allowed to update the data similar data at one time. This gives rise to concurrent update problem. When the user for database connects to it the session formulated are new, not refreshed. For every user or even the same user, a separate session is lodged. In the complicated boundaries of […]

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Differentiation Between The Having Clause And The Group By Statement

In SQL, the group by statement and having clause work together when using aggregate functions like MAX, SUM, AVG, etc. The difference between the ‘group by statement’ and ‘having’ clause is best demonstrated by an example. Just suppose a table named as lab_bonus as shown below. Note that the table has several entries for labors […]

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Difference Between A Subquery And A Derived Table

Both subqueries and derived tables can look same and most of the people think they are the same thing, however there are some major differences. Subquery A subquery is a SELECT statement which is nested within another statement. This is why it’s known as a subquery, because it’s similar to have a query within another query. […]

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What Is The Definition Of A Secondary Key?

In SQL, the term secondary key is often misunderstood. In order to get a clear idea about the concept of secondary key, it is essential to know about the other kinds of keys in the database language. There are basically three kinds of keys in SQL: Primary Key Foreign Key Secondary Key Although there is […]

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Difference Between Uncorrelated Subqueries And Correlated Subqueries

Let’s begin out with an example of what exactly an uncorrelated subquery looks like. After this we will compare uncorrelated subquery with a correlated subquery. Uncorrelated Subquery Illustration Here is an example of few SQL that exemplifies an uncorrelated subquery: Select Merchant.Name from Merchant Where Merchant.ID NOT IN ( Select Requisitions.Merchant_id from Requisitions, Client Where […]

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Differences Between Non-Clustered And Clustered Indexes

A clustered index helps in determining the order in which the rows of the table will be stored on disk. Beside this, it basically stores row level data in the index’s leaf nodes itself. However, a non-clustered index has no impact on which the order of the rows is going to be stored. Advantage of […]

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Natural Key In SQL – Definition And Example

Within the context of data warehouses and SQL, you have probably come across the phrase natural key. Actually, a natural key is a key which is made up of columns having a logical relationship within a table with other columns. Here is an example to explain you natural key in simple English. Example of Natural […]

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