2 Delete and update  Delete a record  Update a record DELETE FROM vet_appt WHERE vet_appt_id = 3; UPDATE animal SET’ gender = “MS” WHERE animal_id = 3 What would happen if you didn’t include a where clause with a delete or update record command?

Query Data From Database  We use the SELECT statement to retrieve information from the database. SELECT attribute/s FROM table/s WHERE (condition)

Simple Select List all the record s (rows) and all attributes (columns) in table: * - WILDCARD SELECT * FROM tableName; Select * from animal

Select Attributes/Fields SELECT fieldNameA, fieldNameB FROM tableName; The order in which you list the attributes will be the order the attributes are displayed.

SELECT flname, ffname FROM faculty;

SELECT ffname, flname FROM faculty;

Select Distinct SELECT sclass FROM student; SC -- SR JR SO FR SELECT DISTINCT sclass FROM student; SC -- SR JR SO FR

Filtering Data: The WHERE Clause SELECT fieldName FROM tableName WHERE fieldName [some condition];  Returns only those records that match the condition

Example 1: Number SELECT sfname, slname, fid FROM student WHERE fid = 1;

Example 2: String SELECT sfname, slname FROM student WHERE sclass= 'SO'; Remember Values in strings are Case sensitive

12 Comparison Operators … A and B - Intersect A OR B –UNION: all of A (including yellow, gray and purple) all of B (including aqua, and purple and gray) C and B

Logical Operators - OR SELECT fieldNameA, fieldNameB FROM tableName WHERE attribute = X or attribute = Y; Must match EITHER Select client_fname, client_lname, add1, city, state, zip From vet_client Where state = ‘NJ’ OR state = ‘PA’ ;

14 Arithmetic Operators – Rules of Precedence  Arithmetic operators and rules of precedence Table 5.5

Logical Operators – AND SELECT fieldNameA, fieldNameB FROM tableName WHERE attribute = X AND attribute = Y; Must match BOTH Select client_fname, client_lname, add1, city, state, zip From vet_client Where state = ‘NJ’ AND state= ‘PA’ ; Would this work?

Logical Operators – AND Select client_fname, client_lname, add1, city, state, zip From vet_client Where city= ‘Philadelphia’ AND state= ‘PA’ ;

Comparison Operators SymbolDescription >Greater Than >=Greater than or equal to <Less Than <=Less than or equal to !=, <>Not equal to INLooks for records with a value which is equal to one of the values in a list BETWEENLooks for records with a value between two different values

SELECT appt_date, appt_type, temperature FROM vet_appt WHERE (temperature >= 102 ; SELECT appt_date, appt_type, temperature FROM vet_appt WHERE appt_type in (1, 2, 3)’ EXAMPLES of Comparison Operator

Logical Operators – AND SELECT fieldNameA, fieldNameB FROM tableName WHERE criteria Select client_fname, client_lname, add1, city, state, zip From vet_client Where state = ‘NJ’ AND fieldNameA = ‘PA’ ; Would this work?

Wildcard Characters _ : 1 character %: multiple characters SELECT client_lname FROM vet_client WHERE client_lname LIKE ‘_emple’; SELECT client_lname FROM vet_client WHERE client_lname LIKE ‘%d%

NULL/NOT NULL Operator SELECT student_fname, student_lname, FROM student WHERE student_mname IS NULL SELECT student_fname, student_lname, FROM student WHERE student_mname IS NOT NULL

Sorting the Output: ORDER BY SELECT client_lname, client_fname ORDER BY client_lname desc; Can Nest order ASC is default

Example: SELECT bldg_code, room, capacity FROM location WHERE capacity >= 40 ORDER BY capacity DESC, bldg_code ASC ; BLDG_CODE ROOM CAPACITY SP BUS BUS SP

To Summarize SELECT (distinct) fieldName/s FROM tableName WHERE fieldName [some condition] ORDER BY fieldName ASC/DESC;