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[sql/en] fix semicolons (#4915)
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Th3G33k committed Apr 27, 2024
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17 changes: 9 additions & 8 deletions sql.html.markdown
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ filename: learnsql.sql
contributors:
- ["Bob DuCharme", "http://bobdc.com/"]
- ["Th3G33k", "https://github.com/Th3G33k"]

---

Structured Query Language (SQL) is an [ISO/IEC 9075](https://www.iso.org/standard/63555.html) standard language for creating and working with databases stored in a set of tables. Implementations usually add their own extensions to the language; [Comparison of different SQL implementations](http://troels.arvin.dk/db/rdbms/) is a good reference on product differences.
Expand Down Expand Up @@ -65,16 +66,16 @@ SELECT DISTINCT title FROM titles ORDER BY title ASC;

-- Use the comparison operators (=, >, <, >=, <=, <>) and
-- the conditional keywords (AND, OR) to refine your queries.
SELECT * FROM departments WHERE dept_no = 'd001' OR dept_no = 'd002'
SELECT * FROM departments WHERE dept_no = 'd001' OR dept_no = 'd002';

-- Same as above.
SELECT * FROM departments WHERE dept_no IN ('d001', 'd0002')
SELECT * FROM departments WHERE dept_no IN ('d001', 'd002');

-- Opposite of the above.
SELECT * FROM departments WHERE dept_no NOT IN ('d001', 'd0002')
SELECT * FROM departments WHERE dept_no NOT IN ('d001', 'd002');

-- Select in a given range.
SELECT * from departments WHERE dept_no BETWEEN 'd001' AND 'd0002'
SELECT * from departments WHERE dept_no BETWEEN 'd001' AND 'd002';

-- Show the number of rows in the departments table.
SELECT COUNT(*) FROM departments;
Expand All @@ -91,15 +92,15 @@ SELECT COUNT(*) FROM departments WHERE dept_name LIKE '%en%';
-- Retrieve the total number of employees, by department number,
-- with the condition of having more than 100 employees.
SELECT dept_no, COUNT(dept_no) FROM dept_emp GROUP BY dept_no
HAVING COUNT(dept_no) > 100
HAVING COUNT(dept_no) > 100;

-- Aliases, using the optional keyword AS, can be used for column/table names.
SELECT COUNT(A.*) AS total_employees, COUNT(B.*) total_departments
FROM employees AS A, departments B
FROM employees AS A, departments B;

-- Common date format is "yyyy-mm-dd".
-- However, it can vary according to the implementation, the operating system, and the session's locale.
SELECT * FROM dept_manager WHERE from_date >= '1990-01-01'
SELECT * FROM dept_manager WHERE from_date >= '1990-01-01';

-- A JOIN of information from multiple tables: the titles table shows
-- who had what job titles, by their employee numbers, from what
Expand All @@ -117,7 +118,7 @@ FROM titles INNER JOIN employees ON
-- UNION selects distinct rows, UNION ALL selects all rows.
SELECT * FROM departments WHERE dept_no = 'd001'
UNION
SELECT * FROM departments WHERE dept_no = 'd002'
SELECT * FROM departments WHERE dept_no = 'd002';

-- SQL syntax order is:
-- SELECT _ FROM _ JOIN _ ON _ WHERE _ GROUP BY _ HAVING _ ORDER BY _ UNION
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