fix(guide): simplify directory structure

guide/english/sql/sql-in-operator/index.md

@@ -0,0 +1,51 @@
+---
+title: SQL In Operator
+---
+## SQL In Operator
+
+## IN Operator defined
+
+The `IN` operator is used in a `WHERE` or `HAVING` (as part of the `GROUP BY`) to limit the selected rows to the items "IN" a list.
+
+Here is the current full student list to compare to the `WHERE` clause result set:
+
+```sql
+select studentID, FullName, sat_score, rcd_updated from student;
+```
+
+```text
++-----------+------------------------+-----------+---------------------+
+| studentID | FullName               | sat_score | rcd_updated         |
++-----------+------------------------+-----------+---------------------+
+|         1 | Monique Davis          |       400 | 2017-08-16 15:34:50 |
+|         2 | Teri Gutierrez         |       800 | 2017-08-16 15:34:50 |
+|         3 | Spencer Pautier        |      1000 | 2017-08-16 15:34:50 |
+|         4 | Louis Ramsey           |      1200 | 2017-08-16 15:34:50 |
+|         5 | Alvin Greene           |      1200 | 2017-08-16 15:34:50 |
+|         6 | Sophie Freeman         |      1200 | 2017-08-16 15:34:50 |
+|         7 | Edgar Frank "Ted" Codd |      2400 | 2017-08-16 15:35:33 |
+|         8 | Donald D. Chamberlin   |      2400 | 2017-08-16 15:35:33 |
+|         9 | Raymond F. Boyce       |      2400 | 2017-08-16 15:35:33 |
++-----------+------------------------+-----------+---------------------+
+9 rows in set (0.00 sec)
+```
+
+Rows will be presented that have an SAT score in this list (1000, 2400):
+
+```sql
+select studentID, FullName, sat_score, rcd_updated
+from student
+where sat_score in (1000, 2400);
+```
+
+```text
++-----------+------------------------+-----------+---------------------+
+| studentID | FullName               | sat_score | rcd_updated         |
++-----------+------------------------+-----------+---------------------+
+|         3 | Spencer Pautier        |      1000 | 2017-08-16 15:34:50 |
+|         7 | Edgar Frank "Ted" Codd |      2400 | 2017-08-16 15:35:33 |
+|         8 | Donald D. Chamberlin   |      2400 | 2017-08-16 15:35:33 |
+|         9 | Raymond F. Boyce       |      2400 | 2017-08-16 15:35:33 |
++-----------+------------------------+-----------+---------------------+
+4 rows in set (0.00 sec)
+```