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What is the operation called to find tuples that satisfy a given condition from a relation in a relational database?
What is the operation called to find tuples that satisfy a given condition from a relation in a relational database?
In a relational database, finding tuples that satisfy given conditions from a relationship is called selection. The condition is given as a logical expression, and the tuple with a true value will be selected.
#The operation of finding tuples that satisfy a given condition from a relationship is called selection. The conditions are given as logical expressions, and the tuples with true values will be selected.
This operation extracts tuples from the horizontal direction. The phrases FOR and WHILE in FOXPRO are equivalent to selection operations.
In a relational database, there are three basic operations on relationships, which are:
1. Selection operation: the operation of finding tuples that meet given conditions from the relationship;
2. Projection operation: the operation of selecting several attributes from a relationship to form a new relationship;
3. Connection operation: the operation of merging two or more relationships into a new relationship based on the associated fields. .
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