Merge #146829 #149890

146829: sql,externalconn: add ALTER EXTERNAL CONNECTION r=msbutler a=edwardguo-crl

## Summary

Add AST parser support for the new SQL command `ALTER EXTERNAL CONNECTION`, allowing users to modify existing external connections.

Fixes #98610

149890: asim: add .txt ending r=tbg a=tbg

We're having issues with Goland and Reviewable classifying some files as binary.

```
find ./pkg/kv/kvserver/asim/tests/testdata -type f -exec mv {} {}.txt ';'
```

Epic: CRDB-25222


Co-authored-by: Edward Guo <[email protected]>
Co-authored-by: Tobias Grieger <[email protected]>

Author: 3 people

docs/generated/sql/bnf/BUILD.bazel

@@ -25,6 +25,7 @@ FILES = [
     "alter_database_to_schema_stmt",
     "alter_ddl_stmt",
     "alter_default_privileges_stmt",
+    "alter_external_connection_stmt",
     "alter_func_stmt",
     "alter_func_options_stmt",
     "alter_func_rename_stmt",

docs/generated/sql/bnf/alter_external_connection_stmt.bnf

@@ -0,0 +1,3 @@
+alter_external_connection_stmt ::=
+	'ALTER' 'EXTERNAL' 'CONNECTION' label_spec 'AS' string_or_placeholder
+	| 'ALTER' 'EXTERNAL' 'CONNECTION' 'IF' 'EXISTS' label_spec 'AS' string_or_placeholder

docs/generated/sql/bnf/alter_stmt.bnf

@@ -1,4 +1,5 @@
 alter_stmt ::=
 	alter_ddl_stmt
+	| alter_external_connection_stmt
 	| alter_role_stmt
 	| alter_virtual_cluster_stmt

docs/generated/sql/bnf/stmt_block.bnf

@@ -193,6 +193,7 @@ legacy_end_stmt ::=
 
 alter_stmt ::=
 	alter_ddl_stmt
+	| alter_external_connection_stmt
 	| alter_role_stmt
 	| alter_virtual_cluster_stmt
 
@@ -560,6 +561,10 @@ alter_ddl_stmt ::=
 	| alter_policy_stmt
 	| alter_job_stmt
 
+alter_external_connection_stmt ::=
+	'ALTER' 'EXTERNAL' 'CONNECTION' label_spec 'AS' string_or_placeholder
+	| 'ALTER' 'EXTERNAL' 'CONNECTION' 'IF' 'EXISTS' label_spec 'AS' string_or_placeholder
+
 alter_role_stmt ::=
 	'ALTER' role_or_group_or_user role_spec opt_role_options
 	| 'ALTER' role_or_group_or_user 'IF' 'EXISTS' role_spec opt_role_options
@@ -1804,6 +1809,10 @@ alter_policy_stmt ::=
 alter_job_stmt ::=
 	'ALTER' 'JOB' a_expr 'OWNER' 'TO' role_spec
 
+label_spec ::=
+	string_or_placeholder
+	| 'IF' 'NOT' 'EXISTS' string_or_placeholder
+
 role_or_group_or_user ::=
 	'ROLE'
 	| 'USER'
@@ -1936,10 +1945,6 @@ target_list ::=
 changefeed_target_expr ::=
 	insert_target
 
-label_spec ::=
-	string_or_placeholder
-	| 'IF' 'NOT' 'EXISTS' string_or_placeholder
-
 logical_replication_resources ::=
 	'TABLE' db_object_name
 	| 'TABLES' '(' logical_replication_resources_list ')'

pkg/gen/bnf.bzl

@@ -25,6 +25,7 @@ BNF_SRCS = [
     "//docs/generated/sql/bnf:alter_database_to_schema_stmt.bnf",
     "//docs/generated/sql/bnf:alter_ddl_stmt.bnf",
     "//docs/generated/sql/bnf:alter_default_privileges_stmt.bnf",
+    "//docs/generated/sql/bnf:alter_external_connection_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_dep_extension_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_options_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_owner_stmt.bnf",

pkg/gen/diagrams.bzl

@@ -26,6 +26,7 @@ DIAGRAMS_SRCS = [
     "//docs/generated/sql/bnf:alter_database_to_schema.html",
     "//docs/generated/sql/bnf:alter_ddl.html",
     "//docs/generated/sql/bnf:alter_default_privileges.html",
+    "//docs/generated/sql/bnf:alter_external_connection.html",
     "//docs/generated/sql/bnf:alter_func.html",
     "//docs/generated/sql/bnf:alter_func_dep_extension.html",
     "//docs/generated/sql/bnf:alter_func_options.html",

pkg/gen/docs.bzl

@@ -35,6 +35,7 @@ DOCS_SRCS = [
     "//docs/generated/sql/bnf:alter_database_to_schema_stmt.bnf",
     "//docs/generated/sql/bnf:alter_ddl_stmt.bnf",
     "//docs/generated/sql/bnf:alter_default_privileges_stmt.bnf",
+    "//docs/generated/sql/bnf:alter_external_connection_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_dep_extension_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_options_stmt.bnf",
     "//docs/generated/sql/bnf:alter_func_owner_stmt.bnf",