Bind DateTime parameters as DATETIME so MariaDB keeps pre-1970 values

docs/src/migration.md

@@ -129,6 +129,7 @@ Deliberate, documented changes relative to Connector/C 1.6.0:
 | BIT decoding | text: first byte only; binary: little-endian | big-endian value of all bytes (≤ 8) in both protocols |
 | BIT parameters | little-endian `bitvalue` encoding | big-endian binary string (matches the decode) |
 | `Bool` parameters | fell through to the `MYSQL_TYPE_STRING` fallback (untested latent bug) | bound as `MYSQL_TYPE_TINY` |
+| `DateTime` parameters | bound as `MYSQL_TYPE_TIMESTAMP`: MariaDB stored NULL for values before 1970 or after 2106 | bound as `MYSQL_TYPE_DATETIME`, like `Timestamp` |
 | TIME decoding | text parse errored on negative/≥24 h; binary ignored sign and days | `Dates.Time` for `0 ≤ t < 24h`, `ConversionError` otherwise; `time_type=Dates.Microsecond` opt-in is lossless and signed |
 | Zero dates | text special-cased only zero DATETIME; text zero DATE failed; binary mapped zero components to 1970 | unified `zero_dates` policy: `:sentinel` (default, `Date(0)` / `Timestamp{P}(0, 1, 1)`), `:missing` (widens column types to `Union{Missing, T}`), `:error`; partial zero dates (`2024-00-05`) are `ConversionError` unless `:missing` |
 | `Base.isopen` | `mysql_ping` round trip | local check only; use `MySQL.ping(conn)` for a round trip |

src/binary.jl

@@ -180,7 +180,9 @@ param_type(::Bit) = return (P.MYSQL_TYPE_BLOB, false)
 param_type(::Vector{UInt8}) = return (P.MYSQL_TYPE_BLOB, false)
 param_type(::DataBytes) = return (P.MYSQL_TYPE_BLOB, false)
 param_type(::Timestamp) = return (P.MYSQL_TYPE_DATETIME, false)
-param_type(::DateTime) = return (P.MYSQL_TYPE_TIMESTAMP, false)
+# DATETIME, not TIMESTAMP: MariaDB turns a TIMESTAMP-typed parameter outside the TIMESTAMP
+# range (before 1970, after 2106) into NULL, even when it is stored in a DATETIME column.
+param_type(::DateTime) = return (P.MYSQL_TYPE_DATETIME, false)
 param_type(::Date) = return (P.MYSQL_TYPE_DATE, false)
 param_type(::Dates.Time) = return (P.MYSQL_TYPE_TIME, false)
 param_type(::AbstractString) = return (P.MYSQL_TYPE_STRING, false)

test/protocol/binary_tests.jl

@@ -996,7 +996,8 @@ end
     @test roundtrip(Timestamp{Microsecond}, Timestamp{Nanosecond}(2024, 1, 2, 1, 2, 3, 456, 789)) === Timestamp{Microsecond}(2024, 1, 2, 1, 2, 3, 456, 789)
     # the wire carries microseconds: a sub-microsecond Timestamp{Nanosecond} is refused, never truncated
     @test_throws InexactError N.encode_param_value!(UInt8[], Timestamp{Nanosecond}(2024, 1, 2, 1, 2, 3, 456, 789, 1))
-    @test N.param_signature(Any[Timestamp{Second}(2024, 1, 1), DateTime(2024, 1, 1)]) == UInt16[P.MYSQL_TYPE_DATETIME, P.MYSQL_TYPE_TIMESTAMP]
+    # DateTime binds as DATETIME: MariaDB nulls TIMESTAMP-typed parameters outside 1970-2106
+    @test N.param_signature(Any[Timestamp{Second}(2024, 1, 1), DateTime(2024, 1, 1)]) == UInt16[P.MYSQL_TYPE_DATETIME, P.MYSQL_TYPE_DATETIME]
     @test roundtrip(Time, Time(13, 14, 15)) == Time(13, 14, 15)
     @test roundtrip(Time, Time(13, 14, 15, 250, 500)) == Time(13, 14, 15, 250, 500)
 

test/user_workflow.jl

@@ -55,6 +55,16 @@ function run_user_workflow(conn)
         @test expected.data == [UInt8[0, 255], UInt8[2], UInt8[3]]
         @test Tables.columntable(DBInterface.execute(conn, "SELECT * FROM items ORDER BY id"; mysql_store_result=false)) == expected
         @test Tables.columntable(DBInterface.execute(conn, "SELECT * FROM items WHERE id > ? ORDER BY id", (0,))) == expected
+        # DateTime parameters before 1970 or after 2106: MariaDB stored NULL for them while they
+        # were sent as MYSQL_TYPE_TIMESTAMP.
+        DBInterface.execute(conn, "DROP TABLE IF EXISTS old_dates")
+        DBInterface.execute(conn, "CREATE TABLE old_dates (id INT PRIMARY KEY, at DATETIME(3))")
+        dates = [DateTime(1955, 3, 4, 5, 6, 7, 890), DateTime(1969, 12, 31, 23, 59, 59), DateTime(2200, 1, 1)]
+        DBInterface.executemany(conn, "INSERT INTO old_dates VALUES (?, ?)", (id=[1, 2, 3], at=dates))
+        @test isequal(Tables.columntable(DBInterface.execute(conn, "SELECT at FROM old_dates ORDER BY id")).at, Timestamp{Millisecond}.(dates))
+        DBInterface.execute(conn, "DROP TABLE IF EXISTS old_dates_load")
+        MySQL.load((id=[1], born=[DateTime(1955, 3, 4)]), conn, "old_dates_load")
+        @test isequal(Tables.columntable(DBInterface.execute(conn, "SELECT born FROM old_dates_load")).born, [Timestamp{Millisecond}(DateTime(1955, 3, 4))])
         @test DBInterface.transaction(conn) do
             DBInterface.execute(conn, "UPDATE items SET label='changed' WHERE id=1")
             :committed