primary key vs unique key inwards SQL
The primary key as well as unique key are 2 of import concepts inwards a relational database as well as used to uniquely position a row inwards a table. Both primary key as well as unique key tin position a row uniquely but at that spot is to a greater extent than or less subtle departure betwixt them which nosotros volition come across inwards this article. In fact, primary key vs unique is a pop SQL interview questions along alongside classics similar truncate vs delete and How to produce out transaction inwards a database, generally asked to fresher as well as 2 to three years sense guys inwards whatever programming language. SQL is non simply express to whatever DBA or PLSQL developer but its an of import science fifty-fifty for Java programmer as well as you lot tin await SQL interview query fifty-fifty inwards many Java interviews.
Some fourth dimension programmer likewise confuses betwixt a unique key as well as a unusual key, which is the primary key of other tables inwards relation, therefore questions similar departure betwixt a primary as well as unusual key or primary as well as unique key, or unusual as well as unique keys are asked to banking concern agree their understanding.
The key affair to recall is that they help to proceed information integrity inwards check. Unique key ensures that no duplicate values are inserted inwards the database, piece a primary as well as unusual key is responsible for maintaining referential integrity.
They likewise used to link 2 tables when you lot are joining them. Btw, at that spot is a slight departure inwards unique key as well as unique key constraint, quondam is a concept piece afterward is an implementation which ensures that no duplicate key is inserted into your tables.
Btw, If you lot are novel to these concepts, I advise you lot to root read MySQL, Oracle or Sybase but at that spot tin live on to a greater extent than than ane unique key per table.
4) The unique key is represented using unique constraint piece a primary key is created using primary key constraint inwards whatever tabular array as well as it's automatically got unique constraint. See
The primary key as well as unique key are 2 of import concepts inwards a relational database as well as used to uniquely position a row inwards a table. Both primary key as well as unique key tin position a row uniquely but at that spot is to a greater extent than or less subtle departure betwixt them which nosotros volition come across inwards this article. In fact, primary key vs unique is a pop SQL interview questions along alongside classics similar truncate vs delete and How to produce out transaction inwards a database, generally asked to fresher as well as 2 to three years sense guys inwards whatever programming language. SQL is non simply express to whatever DBA or PLSQL developer but its an of import science fifty-fifty for Java programmer as well as you lot tin await SQL interview query fifty-fifty inwards many Java interviews.
Some fourth dimension programmer likewise confuses betwixt a unique key as well as a unusual key, which is the primary key of other tables inwards relation, therefore questions similar departure betwixt a primary as well as unusual key or primary as well as unique key, or unusual as well as unique keys are asked to banking concern agree their understanding.
The key affair to recall is that they help to proceed information integrity inwards check. Unique key ensures that no duplicate values are inserted inwards the database, piece a primary as well as unusual key is responsible for maintaining referential integrity.
They likewise used to link 2 tables when you lot are joining them. Btw, at that spot is a slight departure inwards unique key as well as unique key constraint, quondam is a concept piece afterward is an implementation which ensures that no duplicate key is inserted into your tables.
Btw, If you lot are novel to these concepts, I advise you lot to root read MySQL, Oracle or Sybase but at that spot tin live on to a greater extent than than ane unique key per table.
4) The unique key is represented using unique constraint piece a primary key is created using primary key constraint inwards whatever tabular array as well as it's automatically got unique constraint. See
5) Many database engines automatically lay clustered index on the primary key as well as since you lot tin exclusively convey ane clustered index per table, it's non available to whatever other unique key at same time. This is truthful for both Oracle as well as MySQL Server. If you lot desire to larn more, you lot tin check
These were to a greater extent than or less of the difference betwixt primary key as well as unique key inwards SQL or whatever table. It's's ane of those SQL interview questions which you lot don't similar to immature lady earlier going for whatever programming interview or whatever database, SQL interview.
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