SELECT is used to retrieve data from database tables. The basic SELECT statement identifies the fields to retrieve using a field list, the table to select from, and optional clauses to filter rows by criteria, group data, and sort the results. Key clauses include FROM to identify the source table, WHERE to filter rows, GROUP BY to group rows, HAVING to filter groups, and ORDER BY to sequence the results. SELECT statements are typically used to query data and return it in a readable format.

1. CIS-245

2. Used to display data and calculations Main tool for making use of the data that’s stored in tables SELECT can be used as part of other commands

3. SELECT {field list}: What’s returned FROM {data source}: Which table to use WHERE {criteria}: Which rows to include GROUP BY {field list}: How to summarize HAVING {field list}: Which groups to include when grouping ORDER BY {field list}: How to sort

4. FROM – get data from original source(s) WHERE – limit rows to work with GROUP BY – create groups HAVING – limit groups SELECT – specify what to return ORDER BY – specify sorting

5. SELECT starts statement Followed by field list Fields can refer to table fields or calculations created as part of query SELECT can be used by itself: SELECT GetDate()

6. Describes where to find the data Can refer to a table or view View is a pre-defined select query, considered a “virtual” table Basic query typically has SELECT and FROM SELECT * FROM Titles

7. INTO – write results into table DISTINCT – eliminate repeating value(s) or rows AS – name or rename a table or column * - include all fields from source

8. Optional clause can write data from one or more tables into another (new) table Access uses this for Append queries Typically used for Archiving To speed processing by creating temporary or summary tables To organize for reporting

9. Distinct eliminates repeating rows or values Used in SELECT clause SELECT DISTINCT Lastname FROM Persons Ensures that a Lastname is returned once, regardless of how may times that Lastname exists in persons

10. AS is used to create a field name for a calculation or to rename an existing field Also referred to as an alias Use is optional Rename fields in tblPersons: SELECT prs_txtLastname AS LastName FROM tblPersons SELECT prs_txtFirstName FirstName FROM tblPersons

11. * represents all fields in data source Results may differ from what’s expected if fields are added, deleted or order changed SELECT * FROM tblCustomers

12. WHERE limits which rows are included in the result Criteria evaluate to True/False True means row will be used for result, false means row will be excluded Sometimes ‘Predicates’ is used in place of criteria (a predicate is a characteristic that’s true about a row)

13. Relational (=, >, <,<>,>=,<=) Like – compares text patterns Wildcards One Character: _ (underscore) Any combination: % Between – compares to range Is – compares true/false/null In – value is in a list Exists – whether there’s a value

14. SELECT * FROM tblRates WHERE rts_curAmount > 20 SELECT * FROM tblAddresses WHERE add_txtState <> ‘wa’

15. If have more than one test use AND/OR to tie tests together AND : All parts must evaluate to True for a row to be included OR : Any part evaluating to True means a row is included No Precedence NOT returns inverse Not False returns True

16. SELECT * FROM Titles WHERE Price > 20 AND Title LIKE ‘%SQL%’ SELECT * FROM Titles WHERE Not Contract

17. Allows data from tables to be summarized Find rows that share a common value Can discover information about the group using aggregate functions Count Average Max

18. Count number of agreements by Customer: SELECT Count(*) AgreementCount, agr_lngCustomerID FROM tblAgreements GROUP BY agr_lngCustomerID

19. Determines which groups to include Use Criteria similar to Where clause Test characteristics of group using HAVING Tests involve aggregate functions which summarize characteristics of rows Use WHERE to determine which particular rows to include in result

20. Display Employee ID’s of those Employees who have received more than 5 payments: SELECT pmt_lngEmployeeID FROM tblPayments GROUP BY pmt_lngEmployeeID HAVING Count(*) > 5

21. Provides means to sort results by a column (actual or calculated) Default sort order is Ascending ORDER BY pub_date ORDER BY au_lname DESC