identifier case sensitivity

docs-2.0/3.ngql-guide/1.nGQL-overview/identifier-case-sensitivity.md

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+# Identifier Case Sensitivity
+
+## Identifiers are Case-Sensitive
+
+The following statements will not work because they refer to two different spaces, i.e. `my_space` and `MY_SPACE`.
+
+```ngql
+nebula> CREATE SPACE my_space (vid_type=FIXED_STRING(30));
+nebula> use MY_SPACE;
+[ERROR (-8)]: SpaceNotFound:
+```
+
+## Keywords and Reserved Words are Case-Insensitive
+
+The following statements are equivalent since `show` and `spaces` are keywords.
+
+```ngql
+nebula> show spaces;  
+nebula> SHOW SPACES;
+nebula> SHOW spaces;
+nebula> show SPACES;
+```
+
+## Functions are Case-Insensitive
+
+Functions are case-insensitive. For example, `count()`, `COUNT()`, and `couNT()` are equivalent.
+
+```ngql
+nebula> WITH [NULL, 1, 1, 2, 2] As a \
+        UNWIND a AS b \
+        RETURN count(b), COUNT(*), couNT(DISTINCT b);
++----------+----------+-------------------+
+| count(b) | COUNT(*) | couNT(distinct b) |
++----------+----------+-------------------+
+| 4        | 5        | 2                 |
++----------+----------+-------------------+
+```