information technologies and microsoft sql server
DESCRIPTION
Information Technologies and Microsoft SQL Server. Day 2 by Alper Özpınar [email protected]. Parts of a database. Attributes (fields) An attribute or field is a component of a record that describes something about an item. Records A record is the representation of an individual item. - PowerPoint PPT PresentationTRANSCRIPT
Parts of a database
Attributes (fields) An attribute or field is a component of a record that
describes something about an item. Records
A record is the representation of an individual item. Table
A collection of records Database
A collection of tables and rules for accessing the tables
What is a relational database?
Originally developed by E.F. Codd in 1970 Organizes data into tables where each item is
a row and the attributes of the item are in columns.
Different from “flat file” databases because you can define “relationships” between items in different tables.
Parts of a database
Record
Attribute/Field
Tables
• Records become “rows”• Attributes/fields become “columns”• Rules determine the relationship between the tables and tie the data together to form a database
Kinds of Relationships
“One to One” One row of a table matches exactly to another
One person, one id number, one address “One to Many”
One row of a table matches many of another One person, many phone numbers
“Many to Many” One row may match many of another or many
rows match one row of another
Creating a database
What information are we trying to store? How do we describe the information? Phone Book/Contact entries
Name Address Company Phone Number URL/Web Page Age Height (in meters) Birthday When we added the entry
Data Types
Binary Database specific binary objects Pictures, digital signatures, etc.
Boolean True/False values
Character Fixed width or variable size
Numeric Integer, Real (floating decimal point), Money
Temporal Time, Date, Timestamp
Phone Book/Contact Record
Name CharacterAddress
CharacterCompany CharacterPhone Number CharacterURL/Web Page CharacterAge IntegerHeight Real (float)Birthday DateWhen we added the entry Timestamp
Basic SQL Commands
Creating tables with CREATE Adding data with INSERT Viewing data with SELECT Removing data with DELETE Modifying data with UPDATE Destroying tables with DROP
SQL Select
SELECT "column_name" FROM "table_name“ SELECT * FROM customers SELECT name,surname FROM customers
SQL Select & Where
SELECT "column_name"FROM "table_name"WHERE "condition“
SELECT *FROM employeeWHERE salary>1000
SQL Select & Where & Conditions
SELECT "column_name"FROM "table_name"WHERE "simple condition"{[AND|OR] "simple condition"}+
SELECT store_nameFROM Store_InformationWHERE Sales > 1000OR (Sales < 500 AND Sales > 275)
And & Or
Logical Operations 1 and 1 =1 1 and 0 =0 0 and 1 =0 0 and 0 =0 1 or 1 = 1 0 or 1 = 1 1 or 0 = 1 0 or 0 = 0
SQL Select & IN
SELECT "column_name"FROM "table_name"WHERE "column_name" IN ('value1', 'value2', ...)
The number of values in the parenthesis can be one or more, with each values separated by comma. Values can be numerical or characters. If there is only one value inside the parenthesis, this commend is equivalent to
WHERE "column_name" = 'value1'
SQL Between
SELECT "column_name"FROM "table_name"WHERE "column_name" BETWEEN 'value1' AND 'value2‘
SELECT *FROM Store_InformationWHERE Date BETWEEN 'Jan-06-1999' AND 'Jan-10-1999'
SQL Like
LIKE allows you to do a search based on a pattern rather than specifying exactly what is desired (as in IN) or spell out a range (as in BETWEEN). The syntax for is as follows:
SELECT "column_name"FROM "table_name"WHERE "column_name" LIKE {PATTERN}
SELECT *FROM Store_InformationWHERE store_name LIKE '%AN%'
SQL Like
'A_Z': All string that starts with 'A', another character, and end with 'Z'. For example, 'ABZ' and 'A2Z' would both satisfy the condition, while 'AKKZ' would not (because there are two characters between A and Z instead of one).
'ABC%': All strings that start with 'ABC'. For example, 'ABCD' and 'ABCABC' would both satisfy the condition.
'%XYZ': All strings that end with 'XYZ'. For example, 'WXYZ' and 'ZZXYZ' would both satisfy the condition.
'%AN%': All string that contain the pattern 'AN' anywhere. For example, 'LOS ANGELES' and 'SAN FRANCISCO' would both satisfy the condition.
SQL Order By
SELECT "column_name"FROM "table_name"[WHERE "condition"]ORDER BY "column_name" [ASC, DESC]
For more columns ORDER BY "column_name1" [ASC, DESC],
"column_name2" [ASC, DESC] SELECT store_name, Sales, Date
FROM Store_InformationORDER BY Sales DESC
SQL Aggregate Functions
AVG COUNT MAX MIN SUM The syntax for using functions is, SELECT "function type"("column_name")
FROM "table_name" SELECT SUM(Sales) FROM Store_Information
SQL Count
SELECT COUNT("column_name")FROM "table_name"
Select Count(*) from Customers Counts the number of rows in table
Count Distinct
COUNT and DISTINCT can be used together in a statement to fetch the number of distinct entries in a table.
SELECT COUNT(DISTINCT store_name)FROM Store_Information
SQL Group By
SELECT "column_name1", SUM("column_name2")FROM "table_name"GROUP BY "column_name1“
SELECT store_name, SUM(Sales)FROM Store_InformationGROUP BY store_name
SQL Having
Instead of using the WHERE clause in the SQL statement, though, we need to use the HAVING clause, which is reserved for aggregate functions. The HAVING clause is typically placed near the end of the SQL statement, and a SQL statement with the HAVING clause may or may not include the GROUP BY clause. The syntax for HAVING is,
SELECT "column_name1", SUM("column_name2")FROM "table_name"GROUP BY "column_name1"HAVING (arithmetic function condition)
SQL Having
SELECT store_name, SUM(sales)FROM Store_InformationGROUP BY store_nameHAVING SUM(sales) > 1500
SQL Alias
SELECT "table_alias"."column_name1" "column_alias"FROM "table_name" "table_alias"
Two reason to use Change column name Take data from two table or table alias
SELECT A1.store_name Store, SUM(A1.Sales) "Total Sales"FROM Store_Information A1GROUP BY A1.store_name
Joining Tables
Used for combining data from different tables
SQL Join
With tables named A1 and A2 SELECT A1.region_name REGION,
SUM(A2.Sales) SALESFROM Geography A1, Store_Information A2WHERE A1.store_name = A2.store_nameGROUP BY A1.region_name
Different types of JOINs
“Inner Join” Unmatched rows in either table aren’t printed
“Left Outer Join” All records from the “left” side are printed
“Right Outer Join” All records from the “right” side are printed
“Full Outer Join” All records are printed
Multiple Table Join Join records from multiple tables
SQL Union
The purpose of the SQL UNION command is to combine the results of two queries together. In this respect, UNION is somewhat similar to JOIN in that they are both used to related information from multiple tables. One restriction of UNION is that all corresponding columns need to be of the same data type. Also, when using UNION, only distinct values are selected (similar to SELECT DISTINCT).
SQL Union
[SQL Statement 1]UNION[SQL Statement 2]
we want to find out all
the dates where there
is a sales transaction.
SQL Union
SELECT Date FROM Store_InformationUNIONSELECT Date FROM Internet_Sales
Result:
SQL Union ALL
The purpose of the SQL UNION ALL command is also to combine the results of two queries together. The difference between UNION ALL and UNION is that, while UNION only selects distinct values, UNION ALL selects all values.
The syntax for UNION ALL is as follows: [SQL Statement 1]
UNION ALL[SQL Statement 2]
SQL Union All
SELECT Date FROM Store_InformationUNION ALLSELECT Date FROM Internet_Sales
Record Operations
SQL Insert
INSERT INTO table_name (col_name1, … col_namen)
VALUES (value1, …, valuen) INSERT INTO Corvettes(Vette_id,
Body_style, Miles, Year, State)
VALUES (37, 'convertible', 25.5, 1986, 17)
SQL Update
To change one or more values of a row in a table UPDATE table_name SET col_name1 = value1, … col_namen = valuen WHERE col_name = value The WHERE clause is the primary key of the rowto be updated UPDATE Corvettes SET Year = 1996 WHERE Vette_id = 17
SQL Delete
Delete has the following syntax:
delete rel-name where qualification Example: Fire all those sailors whose rating
is less than 2.
delete sailors
where rating < 2