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MSSQL: Support standalone BEGIN...END blocks #2186

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b6f225d
MSSQL: Support standalone BEGIN...END blocks
guan404ming Jan 30, 2026
bf35213
Fix lint error
guan404ming Jan 30, 2026
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17 changes: 16 additions & 1 deletion src/dialect/mssql.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,22 @@ impl Dialect for MsSqlDialect {
}

fn parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
if parser.peek_keyword(Keyword::IF) {
if parser.parse_keyword(Keyword::BEGIN) {
if parser.peek_keyword(Keyword::TRANSACTION)
|| parser.peek_keyword(Keyword::WORK)
|| parser.peek_keyword(Keyword::TRY)
|| parser.peek_keyword(Keyword::CATCH)
|| parser.peek_keyword(Keyword::DEFERRED)
|| parser.peek_keyword(Keyword::IMMEDIATE)
|| parser.peek_keyword(Keyword::EXCLUSIVE)
|| parser.peek_token_ref().token == Token::SemiColon
|| parser.peek_token_ref().token == Token::EOF
{
parser.prev_token();
return None;
}
Some(parser.parse_begin_exception_end())
Comment on lines +148 to +162
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@iffyio iffyio Jan 31, 2026

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would a condition like this do what we want?

if parse.peek_keywords(BEGIN, TRANSACTION) {
    None
} else if parse_keyword(BEGIN) {
    Some(parser.parse_begin_exception_end())
}

its not super clear to me why the current logic looks at WORK, TRY etc keywords?

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@guan404ming guan404ming Jan 31, 2026 •
edited
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Thanks for the review. These keywords are checked because parse_begin() handles more than just BEGIN TRANSACTION. It also handles WORK, TRY, CATCH, DEFERRED, IMMEDIATE, EXCLUSIVE (since MsSql's supports_start_transaction_modifier() returns true), as well as bare BEGIN;. If any of these are missed, they'd be incorrectly routed to parse_begin_exception_end() and fail to parse.

For example, BEGIN TRY ... END TRY is valid MSSQL syntax. If we only check for BEGIN TRANSACTION, then BEGIN TRY would fall through to parse_begin_exception_end(), which would try to parse TRY as a SQL statement and fail. because TRY is supposed to be handled as a

datafusion-sqlparser-rs/src/parser/mod.rs

Lines 17938 to 17939 in c8b7f7c

} else if self.parse_keyword(Keyword::TRY) {
Some(TransactionModifier::Try)

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@guan404ming guan404ming Jan 31, 2026

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Feel free to let me know if there are any not clear, thanks!

} else if parser.peek_keyword(Keyword::IF) {
Some(self.parse_if_stmt(parser))
} else if parser.parse_keywords(&[Keyword::CREATE, Keyword::TRIGGER]) {
Some(self.parse_create_trigger(parser, false))
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71 changes: 71 additions & 0 deletions tests/sqlparser_mssql.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2554,3 +2554,74 @@ fn test_sql_keywords_as_column_aliases() {
}
}
}

#[test]
fn parse_mssql_begin_end_block() {
// Single statement
let sql = "BEGIN SELECT 1; END";
let stmt = ms().verified_stmt(sql);
match &stmt {
Statement::StartTransaction {
begin,
has_end_keyword,
statements,
transaction,
modifier,
..
} => {
assert!(begin);
assert!(has_end_keyword);
assert!(transaction.is_none());
assert!(modifier.is_none());
assert_eq!(statements.len(), 1);
}
_ => panic!("Expected StartTransaction, got: {stmt:?}"),
}

// Multiple statements
let sql = "BEGIN SELECT 1; SELECT 2; END";
let stmt = ms().verified_stmt(sql);
match &stmt {
Statement::StartTransaction {
statements,
has_end_keyword,
..
} => {
assert!(has_end_keyword);
assert_eq!(statements.len(), 2);
}
_ => panic!("Expected StartTransaction, got: {stmt:?}"),
}

// DML inside BEGIN/END
let sql = "BEGIN INSERT INTO t VALUES (1); UPDATE t SET x = 2; END";
let stmt = ms().verified_stmt(sql);
match &stmt {
Statement::StartTransaction {
statements,
has_end_keyword,
..
} => {
assert!(has_end_keyword);
assert_eq!(statements.len(), 2);
}
_ => panic!("Expected StartTransaction, got: {stmt:?}"),
}

// BEGIN TRANSACTION still works
let sql = "BEGIN TRANSACTION";
let stmt = ms().verified_stmt(sql);
match &stmt {
Statement::StartTransaction {
begin,
has_end_keyword,
transaction,
..
} => {
assert!(begin);
assert!(!has_end_keyword);
assert!(transaction.is_some());
}
_ => panic!("Expected StartTransaction, got: {stmt:?}"),
}
}