Intro To SQL ODBC 2/3/2016

Transcription

1 Into To SQL Lori Ivey-Dennings Intro To SQL Lori Ivey-Dennings ODBC ODBC Open Database Connectivity A standard interface for communications between a relational database and an application used to access that data You will need an Oracle PC Client dex.html Reference document Oracle ODBC Configuration and Client Installation Guide (Article # 63429) on PowerSource Link to request ODBC access on PowerSource Link for SSL VPN 1

2 Request ODBC Access from Pearson Request ODBC Access from Pearson ODBC Connection Navigate to Control Panel -> System and Security -> Administrative Tools -> Data Sources (ODBC) Click add either under the User DSN or System DSN tab User DSN is seen only by the user that creates the connection System DSN is seen by all users 2

3 ODBC ODBC ODBC 3

4 SQL Developer SQL Developer is a free tool offered by Oracle Link to download -tools/sql-developer/downloads/index.html SQL Developer SQL Developer 4

5 What is SQL Structured Query Language Language used to Talk to the database It is an ANSI (American National Standards Institute) standard Allows you to retrieve data from the database Relational Database Concepts A database server can contain many databases Databases are collections of tables Tables are two-dimensional with rows and columns Limited mathematical and summary operations Common Variable Types Number() VARCHAR2() Date TIMESTAMP() Blob Clob 5

6 Parts of the SQL Statement Select (Required) What do you want from the table? Your shopping list From (Required) What table are you looking in The name of the grocery store Where (Optional) How do you want to subset or filter the data Do you want the name brand pasta or the store brand pasta Order by (Optional) How do you want the data sorted? Putting your shopping list in alphabetic order Mathematical Functions Relational and Logical Operators 6

7 Compound Conditions Aggregate Functions Simple Select Statement To see all of the data from a particular table use the asterisk Select * From Students; This will return all columns and all rows in the STUDENTS table 7

8 Simple Select Statement Select certain columns Select School_id, Last_Name, First_Name, Student_number From Students; This returns only the columns specified in the Select statement from the STUDENT table. Simple Select Statement Select all columns but limit the number of rows Select * From Students Where Grade_Level = 12; This returns all the columns in the STUDENT table. However, it will only return students in grade 12 Simple Select Statement Select all columns but limit the number of rows Select * From Students Where Grade_Level = 12 AND gender = F ; This returns all the columns in the STUDENT table. However, it will only return female students in grade 12 8

9 Simple Select Statement Sorting the results Select * from Students Where Grade_Level = 12 Order By Last_Name; Question Which statement will give me the Last and First name of the student along with their grade level for all students in school 999? A. Select * from students From Students Where school_id = 999; B. Select last_name, first_name, grade From Students Where school_id = 999; C. Select last_name, first_name, grade_level From Students Where school_id = 999; Wildcards Wildcards can be used to substitute for any other character or characters in a string % _ 9

10 Like The LIKE keyword can be used when you are not sure the exact value Select * from students Where last_name like Smith% ; Select * from students Where first_name like Pa% ; Select * from students Where first_name like %ual% ; Like Select * from students Where last_name like _mith ; Select * from students Where last_name like _m_th ; Question Which statement will return students with a last name of Smith? A. Select * from Students Where last_name like smith ; B. Select * from teachers Where last_name = Smith ; C. Select * from Students Where last_name like Sm% ; 10

11 Date and Mathematical Functions Select s.lastfirst, s.gender, s.grade_level, months_between(sysdate, dob) / 12 as age, round(months_between(sysdate, dob) / 12) as exact_age From students s; Aggregate Functions To find the number of active students in your school Select count(*) from Students Where enroll_status = 0; To find the number of active male and female students in your school Select gender, count(*) from students Where enroll_status = 0 Group By gender; Question Which statement would give me the number of students by their grade level? A. Select count(*) from students; B. Select grade_level, count(*) from students; C. Select school_id, grade_level, count(*) from students; D. Select grade_level, count(*) from students Group By grade_level; 11

12 Keys Primary Key a column or set of columns that uniquely identifies the data in a given row. For the Students, the Key(s) are DCID, ID, or the Student_number Foreign Key a column in a table that is the primary key in another table. Unique Key Unique columns like an ID or student_number fields that can be used to reference a row of data The purpose of these keys is so data can be related across tables, without having to repeat data in every table Joins The tables must have a common key Students to Attendance Students to Incidents Attendance to Incidents Joins Inner Join returns all rows when there is a match in BOTH tables Left Join returns all rows from the left table and the matched rows from the right table Right Join returns all rows from the right table and the matched rows from the left table Full Join returns all rows from both tables 12

13 Join Diagram Joins Select s.lastfirst, s.gender, s.grade_level, sg.course_name, sg.grade, sg.termid From students s Inner Join storedgrades sg On s.id = sg.studentid; More Joins Select t.lastfirst, t.ethnicity, sch.name From teachers t Inner Join schools sch On t.schoolid = sch.school_number ; 13

14 Joins Left Outer Select s.lastfirst, s.gender, s.grade_level, si.admission_status_code From students s Left Outer Join s_nc_studentinfo si On s.dcid = si.studentsdcid; Joins Right Outer Select s.lastfirst, s.gender, s.grade_level, si.admission_status_code From s_nc_studentinfo si Right Outer Join students s On si.studentsdcid = s.dcid; Joins Three Tables Select sch.name, sch.school_number, s.lastfirst, s.gender, s.grade_level, sg.course_name, sg.grade, sg.termid From students s Inner Join storedgrades sg On s.id = sg.studentid Inner Join Schools sch On s.school_id = sch.school_number; 14

15 Question Which of these would be helpful in joining two or more tables together? A. Primary Key B. Foreign Key C. Last_Name and First_Name fields D. Unique Identifier Lab Exercise Questions??? 15