codes added

codes added

Author: Parvathyn-packt

1 - SQL Beginner to Guru MySQL Edition Introduction/4 - Exclusive Slack Group/Private Slack Channel Exclusive to this Course.docx

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+CREATE TABLE tasks (
+  task_name VARCHAR(255),
+  complete BOOLEAN );
+  
+INSERT INTO tasks VALUES ('Study SQL', false);  
+
+SELECT * FROM tasks;
+

1 - SQL Beginner to Guru MySQL Edition Introduction/5 - SQL - Let_s write our first SQL!/AssignmentCreatePersonTable.pdf

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+CREATE TABLE persons (
+	first_name VARCHAR(255),
+	last_name VARCHAR(255)
+);
+
+INSERT INTO persons VALUES ('John', 'Thompson');
+
+SELECT concat(first_name, ' ', last_name) as full_name from persons;

1 - SQL Beginner to Guru MySQL Edition Introduction/5 - SQL - Let_s write our first SQL!/gettingstartedwithsql.txt

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+use employees;
+
+select * from departments;
+
+insert into departments values ('d999', 'foo');
+
+delete from departments where dept_no = 'd999';
+
+
+-- Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column To disable safe mode, toggle the option in Preferences -> SQL Editor and reconnect.
+delete from departments;
+
+-- wont work
+delete from departments where dept_no like '%';
+
+delete from departments where dept_no like 'd%';
+
+
+-- view table information
+SELECT cols.TABLE_NAME, cols.COLUMN_NAME, cols.ORDINAL_POSITION,
+cols.COLUMN_DEFAULT, cols.IS_NULLABLE, cols.DATA_TYPE,
+    cols.CHARACTER_MAXIMUM_LENGTH, cols.CHARACTER_OCTET_LENGTH,
+    cols.NUMERIC_PRECISION, cols.NUMERIC_SCALE,
+    cols.COLUMN_TYPE, cols.COLUMN_KEY, cols.EXTRA,
+    cols.COLUMN_COMMENT, refs.REFERENCED_TABLE_NAME, refs.REFERENCED_COLUMN_NAME,
+    cRefs.UPDATE_RULE, cRefs.DELETE_RULE,
+    links.TABLE_NAME, links.COLUMN_NAME,
+    cLinks.UPDATE_RULE, cLinks.DELETE_RULE
+FROM INFORMATION_SCHEMA.`COLUMNS` as cols
+LEFT JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` AS refs
+ON refs.TABLE_SCHEMA=cols.TABLE_SCHEMA
+    AND refs.REFERENCED_TABLE_SCHEMA=cols.TABLE_SCHEMA
+    AND refs.TABLE_NAME=cols.TABLE_NAME
+    AND refs.COLUMN_NAME=cols.COLUMN_NAME
+LEFT JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS cRefs
+ON cRefs.CONSTRAINT_SCHEMA=cols.TABLE_SCHEMA
+    AND cRefs.CONSTRAINT_NAME=refs.CONSTRAINT_NAME
+LEFT JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` AS links
+ON links.TABLE_SCHEMA=cols.TABLE_SCHEMA
+    AND links.REFERENCED_TABLE_SCHEMA=cols.TABLE_SCHEMA
+    AND links.REFERENCED_TABLE_NAME=cols.TABLE_NAME
+    AND links.REFERENCED_COLUMN_NAME=cols.COLUMN_NAME
+LEFT JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS cLinks
+ON cLinks.CONSTRAINT_SCHEMA=cols.TABLE_SCHEMA
+    AND cLinks.CONSTRAINT_NAME=links.CONSTRAINT_NAME
+WHERE cols.TABLE_SCHEMA=DATABASE()
+    AND cols.TABLE_NAME="employees";
+    
+-- use with caution, will clear whole database    
+delete from employees where emp_no > 1;

1 - SQL Beginner to Guru MySQL Edition Introduction/6 - SQL Fiddle Assignment Review/example.sql

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+use employees;
+
+select * from employees;
+
+INSERT INTO employees SELECT max(emp_no) + 1, '1976-02-02', 'Micheal', 'Weston', 'M', '2015-01-02' FROM employees;
+
+SELECT * from employees where last_name = 'Weston';
+
+UPDATE employees
+SET birth_date = '1976-03-02'
+WHERE emp_no = 500000;
+
+DELETE FROM employees 
+WHERE emp_no = 500000;

10 - Using SQL to Delete Data/3 - Example of the SQL DELETE Statement/examples.sql

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+use employees;
+
+select * from employees;
+
+begin;
+
+INSERT INTO employees SELECT max(emp_no) + 1, '1976-02-02', 'Micheal', 'Weston', 'M', '2015-01-02' FROM employees;
+
+commit;
+
+SELECT * from employees where last_name = 'Weston';
+
+commit;
+
+UPDATE employees
+SET birth_date = '1976-03-02'
+WHERE emp_no = 500000;
+
+DELETE FROM employees 
+WHERE emp_no = 500000;
+
+
+rollback;
+
+-- turn off
+set autocommit=0;
+
+-- turn on
+set autocommit=1;