SQL summary - From relational algebra to SQL Selection C(R...

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From relational algebra to SQL Selection σ C (R) SELECT * FROM R WHERE C; σ Length > 150 (Movies) SELECT * FROM Movies WHERE Length > 150; Conditions allowed in SQL: <, >, <=, >=, = (note – not = =), < > (not equals) Can also take AND and OR of conditions. In MySQL, can have condition: Attribute REGEXP ‘regular expression’. For example, SELECT * FROM Movies WHERE Title REGEXP ‘[aeou]t’; Projection π A1,…,Ak (R) SELECT A1,…,Ak FROM R; π Title,Year (Movies) SELECT Title, Year FROM Movies; Union, Intersection, Difference π Title,Year (Movies) π Title,Year (StarsIn) (SELECT Title, Year FROM Movies) UNION (SELECT Title, Year FROM StarsIn); π Title,Year (Movies) ∩ π Title,Year (StarsIn) (SELECT Title, Year FROM Movies)
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  • Spring '08
  • WILLIAMSON
  • Movies, REGEXP `regular expression

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