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195 lines
3.3 KiB
195 lines
3.3 KiB
# PostGres - Advanced
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## Lesson Objectives - important
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1. Linking Tables
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1. Alias
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1. Indexes
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1. Default Values
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1. Constraints
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1. Distinct
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## Lesson Objectives - good to know about
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1. EER Diagrams
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1. Unions
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1. Truncate
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1. Views
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1. Functions
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1. Stored Procedures
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1. Triggers
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1. Transactions
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1. Locks
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1. Privileges
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1. Denormalization
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1. Excel -> CSV -> MySQL
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## Important
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### Linking Tables
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1. [Some Nice Visuals](http://code.tutsplus.com/articles/sql-for-beginners-part-3-database-relationships--net-8561)
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1. One to Many/Many to One Relationships
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- customer has many orders
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1. One to One Relationships
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- each user has one address
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- only one person at that address
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1. Many to Many Relationships
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- actors and movies
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1. Self Referncing Relationships
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- customer referral
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### Alias
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```sql
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SELECT t1.column1 as col1, t2.column2 as col2
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FROM table1 as t1
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INNER JOIN table2 as t2
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ON t1.common_filed = t2.common_field;
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```
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### Indexes
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1. `CREATE INDEX index_name ON table_name (column_name);`
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1. `CREATE INDEX index_name ON table_name (column1_name, column2_name);`
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1. Primary Key
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1. use `\d table_name` to view indexes
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### Default Values
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```sql
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CREATE TABLE people (id SERIAL, name VARCHAR(16), age INT DEAFULT 0);
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\d people
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INSERT INTO people (name) VALUES ('matt');
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SELECT * FROM people;
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```
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### Constraints
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1. NOT NULL
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1. Unique
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1. Foreign Keys
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```sql
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CREATE TABLE companies(
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id SERIAL,
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name VARCHAR(16) NOT NULL,
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city VARCHAR(16)
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);
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INSERT INTO companies ( city ) VALUES ('Palo Alto');
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CREATE TABLE people(
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id INT,
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name VARCHAR(16),
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email VARCHAR(32) UNIQUE,
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company_id INT REFERENCES companies(id)
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);
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\d people
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INSERT INTO people (name, email, company_id) VALUES ('bob', 'bob@bob.com', 999) -- bad company_id
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INSERT INTO people (name, email, company_id) VALUES ('bob', 'bob@bob.com', 1) -- not unique email
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```
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### Distinct
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```sql
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SELECT DISTINCT city FROM people;
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```
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## Good to Know About
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### EER Diagrams
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### Unions
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```sql
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SELECT name FROM people UNION SELECT name FROM companies; -- show distinct values
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SELECT name FROM people UNION ALL SELECT name FROM companies; -- show duplicates
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```
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### Truncate
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```sql
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TRUNCATE TABLE people; -- delete all data, but don't delete table itself
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```
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### Views
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```sql
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CREATE VIEW new_yorkers AS SELECT * FROM people WHERE city = 'NYC';
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\dv
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SELECT * FROM new_yorkers
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```
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### Functions
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```sql
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CREATE FUNCTION add_numbers(a integer, b integer) RETURNS integer AS $$
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BEGIN
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RETURN a + b;
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END;
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$$ LANGUAGE plpgsql;
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\df
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SELECT add_numbers(2,4);
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```
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### Stored Procedures
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```sql
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CREATE PROCEDURE add_person(new_name VARCHAR(16))
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LANGUAGE plpgsql
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AS $$
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BEGIN
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INSERT INTO people (name) VALUES (new_name);
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END
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$$;
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\df
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call add_person('matt');
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```
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### Triggers
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```sql
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CREATE TABLE backup_people (id INT, name VARCHAR(16), age INT);
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CREATE FUNCTION moveDeleted() RETURNS trigger AS $$
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BEGIN
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INSERT INTO backup_people VALUES (OLD.id, OLD.name, OLD.age);
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RETURN OLD;
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END;
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$$ LANGUAGE plpgsql;
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CREATE TRIGGER archive_person
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BEFORE DELETE on people
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FOR EACH ROW
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EXECUTE PROCEDURE moveDeleted();
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\df
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DELETE FROM people WHERE id = 1;
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```
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### Transactions
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### Locks
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### Privileges
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### Denormalization
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### Excel -> CSV -> MySQL
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### SQL Injection
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