SQL INTERVIEW QUESTION & ANSWERS
| 61. |
What is full outer join? |
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The FULL OUTER JOIN returns all those rows from both the tables, where the rows from one table match with the rows from the other table. |
| 62. |
What is Equi Join? |
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An equijoin contains equality operator {=) in the join condition which is used to match rows from different tables. |
| 63. |
What is semijoin? |
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A semijoin between two tables returns the rows from the first table having one or more matches in the second table. Semijoins are written using the EXISTS or IN operator. |
| 64. |
What is self joins? |
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The self join joins a table to itself. It means that a self join joins one row of a table with another row in the same table. It compares one row of a table to itself or with the other rows in the same table. This table appears twice or more times in the FROM clause and is followed by table aliases that qualify column names in the join condition and the SELECT clause.
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| 65. |
What is cartesian join? |
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The cartesian join occurs when you select data from two tables and there is no join condition. It is a join of every row of a table with every row of another table. This only happens, when no matching join columns are specified in the join condition for the table listed in the FROM clause.
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