3 Day Training
Databases and Scripting
What is a Database?
A structured collection of records or data that is organized for efficient storage
and retrieval. There are several common types of databases, and each type has
its own data model (how the data is structured).
The Relational Model is the most commonly used. Common examples are
MySQL, Microsoft SQL Server, and Oracle.
Tables
The foundation of every database system is a table. Every database consists of
one or more tables, which store the database’s data. Each table is identified by a
name (e.g. "Customers" or "Orders") and consists of columns and rows.
The database table columns have their own unique names and data types. Table
columns can have various attributes defining the column functionality (a primary
key, an index on the column, a certain default value, etc.). While columns
describe the data types, the rows contain the actual data.
Relational Database
A relational database consists of separate tables, having explicitly defined
relationships, and whose elements may be combined through queries. Here we
have a downtime event table that is related to a specific piece of equipment.
The main benefit comes from saving storage space. We are storing the
Equipment details once, and being able to retrieve them for each downtime
record.
What is SQL?
SQL or Structured Query Language is a standard computer language for
accessing and manipulating database systems. SQL statements are used to
create, maintain and query relational databases.
There are 4 types of commands and we will be using all of them.
Examples:
• SELECT Firstname FROM Contacts WHERE Lastname = ‘Smith’
• INSERT INTO Contacts VALUES (‘Joe’, ‘Smith’)
• UPDATE Contacts SET Lastname = ‘Howard’ WHERE ID = 1
• DELETE FROM Contacts WHERE Lastname = ‘Smith’
SELECT
The SELECT statement is used to fetch data from a database. The result is stored
in a result table, called the result-set. The SELECT clause allows you to get all
columns (*), or a list of column names.
You also have access to many functions to concatenate, do math, alias column
names, and much more.
Examples:
SELECT * FROM Customers
SELECT Name, Address FROM Customers
SELECT SUM(duration) as ‘Total Seconds’ FROM Downtime
WHERE Clause
The WHERE clause is used to filter only those records that match a certain
criteria. Operators Allowed in the WHERE clause:
= - Equal
> - Greater than
>= - Greater than or equal
BETWEEN - Between an inclusive range
IN - Value in a list of values
<> - Not equal
< - Less than
<= - Less than or equal
LIKE - Search for a pattern
AND & OR operators are used to filter records based on more than one condition.
Examples:
SELECT * FROM Customers WHERE State = ‘CA’
SELECT * FROM Customers WHERE Address LIKE ‘%St%’ AND State = ‘CA’
UPDATE
The UPDATE statement is used to update records in a table. If a WHERE clause is
not used, all records will be updated.
Examples:
UPDATE Customers SET Name = ‘Inductive Automation’
UPDATE Customers SET Address = ‘2110 21st Street’ WHERE ID = 1
INSERT
The INSERT statement is used to insert a new row in a table. You can optionally
use sub-queries to fill in your values.
Example:
INSERT INTO Customers
(Name, Address, City, State, Zip, Country, Phone)
VALUES
(‘Inductive Automation’, ‘2110 21st Street’, ‘Sacramento’, ‘CA’, ‘95818’,
NULL, ‘800-266-7798’)
INSERT INTO Customers VALUES (SELECT * FROM OtherCustomers)
DELETE
The DELETE statement is used to delete records in a table. If a WHERE clause is
not used, all records will be deleted!
Examples:
DELETE FROM Customers
DELETE FROM Customers WHERE Name = ‘Inductive Automation’
ORDER BY Clause
The ORDER BY keyword is used to sort the result-set by a specified column. The
ORDER BY keyword sort the records in ascending order by default. If you want to
sort the records in a descending order, you can use the DESC keyword.
Examples:
SELECT * FROM Customers ORDER BY State ASC, Name ASC
SELECT * FROM history ORDER BY timestamp DESC
JOIN
The JOIN keyword is used in an SQL statement to combine data from two or more
Tables based on a specific condition. The purpose is to bind data together, across tables,
without repeating all of the data in every table. It is common to alias the table names for
shorter column names.
• INNER JOIN: Return any rows where the ON condition is true
• LEFT JOIN: Return all rows from the left table (downtime in the example below), and attach
data from the right table where the ON condition is true
• RIGHT JOIN: Return all rows from the right table (equipment in the example below), and
attach data from the left table where the ON condition is true
• FULL JOIN: Return all rows from both tables and join data where the ON condition is true
Example:
SELECT * FROM downtime d INNER JOIN equipment e
ON e.ID = d.equipmentID
GROUP BY Clause
The GROUP BY statement is used in conjunction with the aggregate functions to
group the result-set by one or more columns.
Example:
SELECT CauseID, SUM(Duration) FROM Downtime GROUP BY CauseID
Example
Bringing it all together, you can have complicated queries that return very useful
information.
SELECT
FROM
d.ID,
e.Name as ‘Equipment Name’,
SUM(d.Duration) as ‘Total Seconds’
Downtime d
INNER JOIN
Equipment e ON d.EquipmentID = e.ID
WHERE
e.Name LIKE ‘%Filler%’
GROUP BY
e.Name ASC
Further Help
Inductive Automation
http://www.inductiveautomation.com
(800) 266-7798 - Press 2 for Technical Support
support@inductiveautomation.com
SQL Tutorials
http://www.sqlzoo.net
http://www.w3schools.com/sql