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Common Mathematical Symbols Used in Michael Sipser’s Introduction to the Theory of Computation

This is a short list of logical symbols that appear in Michael Sipser's book Introduction to the Theory of Computation.

Name	Symbol	Description
Alphabetical Set	Σ or Γ	Often used to designate a set containing an alphabet.
Boolean Conjunction	∧	If both values surrounding ∧ are true, then the result is true (AND).
Boolean Disjunction	∨	If both values surrounding ∨ are opposites, then the result is true (OR).
Boolean Equality	⇔	If both values surrounding ⇔ have the same value, then the result is true.

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Using Left Join/Right Join to Join Two Tables on a Common Column, and to Default to Null For Missing Values in MySQL

The following SQL schema will produce the two tables.

Create table If Not Exists Employees (id int, name varchar(20));
Create table If Not Exists EmployeeUNI (id int, unique_id int);
Truncate table Employees;
insert into Employees (id, name) values ('1', 'Alice');
insert into Employees (id, name) values ('7', 'Bob');

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Using Math Operations in MySQL Queries

The following SQL schema will produce the table below.

CREATE TABLE IF NOT EXISTS Employees(
  emp_id INT,
  event_day DATE,
  in_time INT,
 out_time INT

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Aliasing in MySQL

The following SQL schema will populate the table below.

CREATE TABLE IF NOT EXISTS DailySales(
  date_id date,
  make_name varchar(20),
  lead_id int,
  partner_id int

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Using the Count Function in MySQL

The following SQL schema will populate the table below.

CREATE TABLE IF NOT EXISTS DailySales(
  date_id date,
  make_name varchar(20),
  lead_id int,

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Using DISTINCT in MySQL

The following SQL schema will populate the table below.

CREATE TABLE IF NOT EXISTS DailySales(
  date_id date,
  make_name varchar(20),
  lead_id int,
  partner_id int

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OpenGL ES Storage Qualifiers

Name	Type	Keyword	Description

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Using the Date Type in MySQL

The DATE type takes in a string value and converts it into a YYYY-MM-DD date format.

Let's say we have a SQL schema that uses the DATE type, and that inserts one row.

CREATE TABLE IF NOT EXISTS DailySales(
  date_id DATE,
  make_name VARCHAR(20),

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Checking the Length of a String in a MySQL Where Clause

Let's say we have a SQL schema like this:

Create table If Not Exists Tweets(tweet_id int, content varchar(50));
Truncate table Tweets;
insert into Tweets (tweet_id, content) values ('1', 'Vote for Biden');
insert into Tweets (tweet_id, content) values ('2', 'Let us make America great again!');

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Using Order By to Sort MySQL Table Results by Ascending or Descending Order

The following statement will create a new table Products and insert values into it.

CREATE TABLE IF NOT EXISTS Products (
  product_id int,
  low_fats ENUM('Y', 'N'),
  recyclable ENUM('Y', 'N')
);