mvzink opened a new issue, #1697:
URL: https://github.com/apache/datafusion-sqlparser-rs/issues/1697
sqlparser currently accepts Postgres-style `set variable = expr` and
Snowflake-style `set (variable, other_variable) = (expr, expr)` syntax. It also
accepts MySQL-style `set variable = expr, other_variable = expr` syntax, but
not in the way one might expect: `other_variable = expr` becomes another
expression in the list of values.
```
cargo run --example cli - --mysql
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s
Running `target/debug/examples/cli - --mysql`
Parsing from stdin using MySqlDialect
set @foo = 'bar', @baz = 'quux';
2025-01-31T18:01:10.029Z DEBUG [sqlparser::parser] Parsing sql 'set @foo =
'bar', @baz = 'quux';
'...
2025-01-31T18:01:10.033Z DEBUG [sqlparser::parser] parsing expr
2025-01-31T18:01:10.033Z DEBUG [sqlparser::parser] prefix:
Value(SingleQuotedString("bar"))
2025-01-31T18:01:10.033Z DEBUG [sqlparser::dialect]
get_next_precedence_full() TokenWithSpan { token: Comma, span:
Span(Location(1,17)..Location(1,18)) }
2025-01-31T18:01:10.033Z DEBUG [sqlparser::parser] next precedence: 0
2025-01-31T18:01:10.033Z DEBUG [sqlparser::parser] parsing expr
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] prefix: Identifier(Ident
{ value: "@baz", quote_style: None, span: Span(Location(1,19)..Location(1,23))
})
2025-01-31T18:01:10.034Z DEBUG [sqlparser::dialect]
get_next_precedence_full() TokenWithSpan { token: Eq, span:
Span(Location(1,24)..Location(1,25)) }
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] next precedence: 20
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] parsing expr
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] prefix:
Value(SingleQuotedString("quux"))
2025-01-31T18:01:10.034Z DEBUG [sqlparser::dialect]
get_next_precedence_full() TokenWithSpan { token: SemiColon, span:
Span(Location(1,32)..Location(1,33)) }
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] next precedence: 0
2025-01-31T18:01:10.034Z DEBUG [sqlparser::dialect]
get_next_precedence_full() TokenWithSpan { token: SemiColon, span:
Span(Location(1,32)..Location(1,33)) }
2025-01-31T18:01:10.034Z DEBUG [sqlparser::parser] next precedence: 0
Round-trip:
'SET @foo = 'bar', @baz = 'quux''
Parse results:
[
SetVariable {
scope: None,
hivevar: false,
variables: One(
ObjectName(
[
Identifier(
Ident {
value: "@foo",
quote_style: None,
span: Span(Location(1,5)..Location(1,9)),
},
),
],
),
),
value: [
Value(
SingleQuotedString(
"bar",
),
),
BinaryOp {
left: Identifier(
Ident {
value: "@baz",
quote_style: None,
span: Span(Location(1,19)..Location(1,23)),
},
),
op: Eq,
right: Value(
SingleQuotedString(
"quux",
),
),
},
],
},
]
```
This round-trips okay, and could be sufficient for many use cases if they
are willing to decipher the binary operators in the expressions. However, it
might be appropriate to represent this differently in the AST, along the lines
of:
```
SetVariables {
assignments: [
(
Variable {
scope: User,
name: Ident {
value: "foo",
},
},
Expr {
value: Value(
SingleQuotedString(
"bar",
),
),
},
),
(
Variable {
scope: User,
name: Ident {
value: "baz",
},
},
Expr {
value: Value(
SingleQuotedString(
"quux",
),
),
},
),
],
},
```
This could be a bit annoying to parse unless we simply switch on the dialect
at the very start of `parse_set` (MySQL doesn't support either Postgres- or
Snowflake-style assignments).
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