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[CALCITE-7456] Enable the TRY_CAST function to support the MSSQL dialect #4856

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[CALCITE-7456] Enable the TRY_CAST function to support the MSSQL dialect #4856

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c4f7b4c
[CALCITE-7456] Improve the conversion of try_cast function with MSSQL
Mar 30, 2026
2e1c885
[CALCITE-7456] Enable the TRY_CAST function to support the MSSQL dialect
Mar 31, 2026
ffe8d86
Remove the parentheses from the judgment
Apr 1, 2026
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7 changes: 7 additions & 0 deletions core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
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Expand Up @@ -172,6 +172,13 @@ public MssqlSqlDialect(Context context) {
final SqlWriter.Frame frame = writer.startFunCall("CEILING");
call.operand(0).unparse(writer, leftPrec, rightPrec);
writer.endFunCall(frame);
} else if (call.getKind() == SqlKind.SAFE_CAST) {
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@caicancai caicancai Apr 2, 2026

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Manually assembling unparsed logic is repetitive and fragile.

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@xiedeyantu xiedeyantu Apr 2, 2026

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I researched other dialects, and they almost all use writer.startFunCall to rewrite functions. I am not sure this is good way, but this is the current reality.

// TRY_CAST is supported but not SAFE_CAST in MS SQL
final SqlWriter.Frame frame = writer.startFunCall("TRY_CAST");
call.operand(0).unparse(writer, leftPrec, rightPrec);
writer.sep("as");
call.operand(1).unparse(writer, leftPrec, rightPrec);
writer.endFunCall(frame);
} else {
switch (call.getKind()) {
case FLOOR:
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12 changes: 12 additions & 0 deletions core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
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Expand Up @@ -12025,4 +12025,16 @@ public Sql schema(CalciteAssert.SchemaSpec schemaSpec) {
sql(query).withLibrary(SqlLibrary.HIVE).withHive().ok(expectedHive);
sql(query).withLibrary(SqlLibrary.SPARK).withSpark().ok(expectedSpark);
}

/** Test case for
* <a href="https://issues.apache.org/jira/browse/CALCITE-7456">[CALCITE-7456]
* Enable the TRY_CAST function to support the MSSQL dialect</a>. */
@Test void testTryCastWithMssql() {
final String query = "select TRY_CAST(\"gross_weight\" as bigint) as gross_weight_value\n"
+ "from \"product\"";
final String expectedSql = "SELECT TRY_CAST([gross_weight] AS BIGINT) AS [GROSS_WEIGHT_VALUE]"
+ "\nFROM [foodmart].[product]";

sql(query).withLibrary(SqlLibrary.MSSQL).withMssql().ok(expectedSql);
}
}
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