summaryrefslogtreecommitdiffhomepage
path: root/sql.html.markdown
diff options
context:
space:
mode:
authorAdam Bard <adam@adambard.com>2018-11-04 09:26:31 -0800
committerAdam Bard <adam@adambard.com>2018-11-04 09:26:31 -0800
commiteabb26c70eb207d98ebf5e14e8f1d94dfeb61c76 (patch)
tree3755509a29213780782ad1d68ec11154b46365d7 /sql.html.markdown
parentdeef75b16e50b8d8c31c001003712b950daebf74 (diff)
Use dash commenting on sql doc instead
Diffstat (limited to 'sql.html.markdown')
-rw-r--r--sql.html.markdown82
1 files changed, 41 insertions, 41 deletions
diff --git a/sql.html.markdown b/sql.html.markdown
index 0638a731..200f4f98 100644
--- a/sql.html.markdown
+++ b/sql.html.markdown
@@ -13,93 +13,93 @@ Several of these sample commands assume that the [MySQL employee sample database
```sql
-# Comments start with a pound sign. End each command with a semicolon.
+-- Comments start with two hyphens. End each command with a semicolon.
-# SQL is not case-sensitive about keywords. The sample commands here
-# follow the convention of spelling them in upper-case because it makes
-# it easier to distinguish them from database, table, and column names.
+-- SQL is not case-sensitive about keywords. The sample commands here
+-- follow the convention of spelling them in upper-case because it makes
+-- it easier to distinguish them from database, table, and column names.
-# Create and delete a database. Database and table names are case-sensitive.
+-- Create and delete a database. Database and table names are case-sensitive.
CREATE DATABASE someDatabase;
DROP DATABASE someDatabase;
-# List available databases.
+-- List available databases.
SHOW DATABASES;
-# Use a particular existing database.
+-- Use a particular existing database.
USE employees;
-# Select all rows and columns from the current database's departments table.
-# Default activity is for the interpreter to scroll the results on your screen.
+-- Select all rows and columns from the current database's departments table.
+-- Default activity is for the interpreter to scroll the results on your screen.
SELECT * FROM departments;
-# Retrieve all rows from the departments table,
-# but only the dept_no and dept_name columns.
-# Splitting up commands across lines is OK.
+-- Retrieve all rows from the departments table,
+-- but only the dept_no and dept_name columns.
+-- Splitting up commands across lines is OK.
SELECT dept_no,
dept_name FROM departments;
-# Retrieve all departments columns, but just 5 rows.
+-- Retrieve all departments columns, but just 5 rows.
SELECT * FROM departments LIMIT 5;
-# Retrieve dept_name column values from the departments
-# table where the dept_name value has the substring "en".
+-- Retrieve dept_name column values from the departments
+-- table where the dept_name value has the substring "en".
SELECT dept_name FROM departments WHERE dept_name LIKE "%en%";
-# Retrieve all columns from the departments table where the dept_name
-# column starts with an "S" and has exactly 4 characters after it.
+-- Retrieve all columns from the departments table where the dept_name
+-- column starts with an "S" and has exactly 4 characters after it.
SELECT * FROM departments WHERE dept_name LIKE "S____";
-# Select title values from the titles table but don't show duplicates.
+-- Select title values from the titles table but don't show duplicates.
SELECT DISTINCT title FROM titles;
-# Same as above, but sorted (case-sensitive) by the title values.
+-- Same as above, but sorted (case-sensitive) by the title values.
SELECT DISTINCT title FROM titles ORDER BY title;
-# Show the number of rows in the departments table.
+-- Show the number of rows in the departments table.
SELECT COUNT(*) FROM departments;
-# Show the number of rows in the departments table that
-# have "en" as a substring of the dept_name value.
+-- Show the number of rows in the departments table that
+-- have "en" as a substring of the dept_name value.
SELECT COUNT(*) FROM departments WHERE dept_name LIKE "%en%";
-# A JOIN of information from multiple tables: the titles table shows
-# who had what job titles, by their employee numbers, from what
-# date to what date. Retrieve this information, but instead of the
-# employee number, use the employee number as a cross-reference to
-# the employees table to get each employee's first and last name
-# instead. (And only get 10 rows.)
+-- A JOIN of information from multiple tables: the titles table shows
+-- who had what job titles, by their employee numbers, from what
+-- date to what date. Retrieve this information, but instead of the
+-- employee number, use the employee number as a cross-reference to
+-- the employees table to get each employee's first and last name
+-- instead. (And only get 10 rows.)
SELECT employees.first_name, employees.last_name,
titles.title, titles.from_date, titles.to_date
FROM titles INNER JOIN employees ON
employees.emp_no = titles.emp_no LIMIT 10;
-# List all the tables in all the databases. Implementations typically provide
-# their own shortcut command to do this with the database currently in use.
+-- List all the tables in all the databases. Implementations typically provide
+-- their own shortcut command to do this with the database currently in use.
SELECT * FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE='BASE TABLE';
-# Create a table called tablename1, with the two columns shown, for
-# the database currently in use. Lots of other options are available
-# for how you specify the columns, such as their datatypes.
+-- Create a table called tablename1, with the two columns shown, for
+-- the database currently in use. Lots of other options are available
+-- for how you specify the columns, such as their datatypes.
CREATE TABLE tablename1 (`fname` VARCHAR(20),`lname` VARCHAR(20));
-# Insert a row of data into the table tablename1. This assumes that the
-# table has been defined to accept these values as appropriate for it.
+-- Insert a row of data into the table tablename1. This assumes that the
+-- table has been defined to accept these values as appropriate for it.
INSERT INTO tablename1 VALUES('Richard','Mutt');
-# In tablename1, change the fname value to "John"
-# for all rows that have an lname value of "Mutt".
+-- In tablename1, change the fname value to "John"
+-- for all rows that have an lname value of "Mutt".
UPDATE tablename1 SET fname="John" WHERE lname="Mutt";
-# Delete rows from the tablename1 table
-# where the lname value begins with "M".
+-- Delete rows from the tablename1 table
+-- where the lname value begins with "M".
DELETE FROM tablename1 WHERE lname like "M%";
-# Delete all rows from the tablename1 table, leaving the empty table.
+-- Delete all rows from the tablename1 table, leaving the empty table.
DELETE FROM tablename1;
-# Remove the entire tablename1 table.
+-- Remove the entire tablename1 table.
DROP TABLE tablename1;
```