add check inequality git til

Author: ronthetech

postgresql/check-inequality.md

@@ -0,0 +1,17 @@
+# How to Check Inequality
+
+---
+
+Like many other languages, PostgreSQL supports the `!=` comparison operator.
+
+```sql
+> select datatype != datatype;
+```
+
+PostgreSQL also supports the `<>` comparison operator, and actually converts `!=` into `<>` during parsing.
+
+```sql
+> select datatype <> datatype;
+```
+
+[link]()