Merge pull request #105 from Altinity/ashwini-ahire7-patch-2

Update ansi-sql-mode.md

content/en/altinity-kb-queries-and-syntax/ansi-sql-mode.md

@@ -4,13 +4,49 @@ linkTitle: "ANSI SQL mode"
 description: >
     ANSI SQL mode
 ---
-It's possible to tune some settings which would make ClickHouse® more ANSI SQL compatible(and slower):
+To make ClickHouse® more compatible with ANSI SQL standards (at the expense of some performance), you can adjust several settings. These configurations will bring ClickHouse closer to ANSI SQL behavior but may introduce a slowdown in query performance:
 
 ```sql
-SET join_use_nulls=1; -- introduced long ago
-SET cast_keep_nullable=1; -- introduced in 20.5
-SET union_default_mode='DISTINCT'; -- introduced in 21.1
-SET allow_experimental_window_functions=1; -- introduced in 21.3
-SET prefer_column_name_to_alias=1; -- introduced in 21.4;
-SET group_by_use_nulls=1; -- introduced in 22.7;
+join_use_nulls=1
 ```
+Introduced in: early versions
+Ensures that JOIN operations return NULL for non-matching rows, aligning with standard SQL behavior.
+
+
+```sql
+cast_keep_nullable=1
+```
+Introduced in: v20.5
+Preserves the NULL flag when casting between data types, which is typical in ANSI SQL.
+
+
+```sql
+union_default_mode='DISTINCT'
+```
+Introduced in: v21.1
+Makes the UNION operation default to UNION DISTINCT, which removes duplicate rows, following ANSI SQL behavior.
+
+
+```sql
+allow_experimental_window_functions=1
+```
+Introduced in: v21.3
+Enables support for window functions, which are a standard feature in ANSI SQL.
+
+
+```sql
+prefer_column_name_to_alias=1
+```
+Introduced in: v21.4
+This setting resolves ambiguities by preferring column names over aliases, following ANSI SQL conventions.
+
+
+```sql
+group_by_use_nulls=1
+```
+Introduced in: v22.7
+Allows NULL values to appear in the GROUP BY clause, consistent with ANSI SQL behavior.
+
+By enabling these settings, ClickHouse becomes more ANSI SQL-compliant, although this may come with a trade-off in terms of performance. Each of these options can be enabled as needed, based on the specific SQL compatibility requirements of your application.
+
+