(WIP) Adds support for generated columns in mysql (in create statements)

src/sqlfluff/dialects/dialect_mysql.py

@@ -315,6 +315,34 @@ class AliasExpressionSegment(BaseSegment):
  Dedent,
  )
 
+# Mainly adapted from the sparksql implementation
+class GeneratedColumnDefinitionSegment(BaseSegment):
+ """A generated column definition.
+
+ e.g. email_domain CHAR(100) AS (SUBSTRING_INDEX(email, '@', -1))
+ https://dev.mysql.com/doc/refman/8.0/en/create-table-generated-columns.html
+ """
+ type = "generated_column_definition"
+
+ match_grammar: Matchable = Sequence(
+ Ref("SingleIdentifierGrammar"), # Column name
+ Ref("DatatypeSegment"), # Column type
+ Bracketed(Anything(), optional=True), # For types like VARCHAR(100)
+ Sequence(
+ Sequence("GENERATED", "ALWAYS", optional=True),
+ "AS",
+ Bracketed(
+ OneOf(
+ Ref("FunctionSegment"),
+ Ref("BareFunctionSegment"),
+ ),
+ ),
+ OneOf("VIRTUAL", "STORED", optional=True)
+ ),
+ AnyNumberOf(
+ Ref("ColumnConstraintSegment", optional=True),
+ ),
+ )
 
 class ColumnDefinitionSegment(BaseSegment):
  """A column definition, e.g. for CREATE TABLE or ALTER TABLE."""
@@ -380,6 +408,8 @@ class CreateTableStatementSegment(ansi.CreateTableStatementSegment):
  https://dev.mysql.com/doc/refman/8.0/en/create-table.html
  """
 
+ # TODO check if here is the right place to add the new option of the
+ # generated column definition
  match_grammar = ansi.CreateTableStatementSegment.match_grammar.copy(
  insert=[
  AnyNumberOf(

test/fixtures/dialects/mysql/create_table_generated_columns.sql

@@ -0,0 +1,7 @@
+
+CREATE TABLE emails (
+ email CHAR(100) NOT NULL,
+ email_domain CHAR(100) AS (SUBSTRING_INDEX(email, '@', -1)),
+ email_domain2 CHAR(100) GENERATED ALWAYS AS (SUBSTRING_INDEX(email, '@', -1)) STORED,
+ email_domain3 CHAR(100) GENERATED ALWAYS AS (SUBSTRING_INDEX(email, '@', -1)) VIRTUAL
+);