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Adam Bard 2018-11-04 09:37:45 -08:00
parent eabb26c70e
commit f363c6459f
1 changed files with 12 additions and 12 deletions
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sql.html.markdown
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@ -27,7 +27,7 @@ DROP DATABASE someDatabase;
SHOW DATABASES;
-- Use a particular existing database.
USE employees;
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.
@ -43,12 +43,12 @@ SELECT dept_no,
SELECT * FROM departments LIMIT 5;
-- 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%";
-- 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.
SELECT * FROM departments WHERE dept_name LIKE "S____";
-- 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 DISTINCT title FROM titles;
@ -60,8 +60,8 @@ SELECT DISTINCT title FROM titles ORDER BY title;
SELECT COUNT(*) FROM departments;
-- 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%";
-- 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
@ -89,13 +89,13 @@ CREATE TABLE tablename1 (`fname` VARCHAR(20),`lname` VARCHAR(20));
-- 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".
UPDATE tablename1 SET fname="John" WHERE lname="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 FROM tablename1 WHERE lname like "M%";
-- 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 FROM tablename1;