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Published byToby Dennis Modified over 8 years ago
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1 SQL Chapter 9 – 8 th edition With help from Chapter 2 – 10 th edition
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2 SQL Is not a complete programming language Is a data sublanguage Used in Microsoft Access when you –create a form –create a report –run a query Access generates SQL and sends it to –Jet which is Access’ internal DBMS engine
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3 Tables on page 237 STUDENT ENROLLMENT CLASS
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4 Projections using SQL SELECT FROM Note: don’t confuse the keyword SELECT with the relational algebra operator selection
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5 SELECT Is an SQL verb than can be used to perform a relational algebra –projection –selections –other actions Note: Selection differs from SELECT because it is the relational algebra operation of obtaining a subset of rows from a table.
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6 SELECT doesn’t automatically remove duplicate rows use keyword DISTINCT if you want duplicate rows removed
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7 Selection using SELECT SELECT FROM WHERE
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8 Selection of all SELECT * FROM WHERE
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9 Selection SELECT FROM WHERE
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10 WHERE clause can have multiple conditions WHERE AND
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11 WHERE clause can refer to a set of values WHERE IN [value1, value2,…]
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12 WHERE can use BETWEEN which is inclusive of endpoints WHERE BETWEEN AND
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13 LIKE
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14 Other possibilities missing values are looked for using IS NULL single column sorting is done using ORDER BY multiple column sorting is done using ORDER BY
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15 SQL Built-in Functions COUNT (*) COUNT
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