From f334474802d22cc40e38476091a68e5135d4b03f Mon Sep 17 00:00:00 2001
From: Alexandru Diaconu <alexandrudiaconu93@gmail.com>
Date: Sun, 15 Mar 2026 12:42:54 +0200
Subject: [PATCH] MDEV-38792 TO_DATE: Inconsistent treatment of separators

Fixed a bug where TO_DATE (Oracle mode) returned NULL if the input string
had extra separators (like '-') not defined in the format. Added a loop
to skip non-alphanumeric characters, making the data parsing just as
flexible as the format parsing.

Signed-off-by: Alexandru Diaconu <alexandrudiaconu93@gmail.com>
---
 mysql-test/main/mdev-38792.result | 10 ++++++++++
 mysql-test/main/mdev-38792.test   | 11 +++++++++++
 sql/item_timefunc.cc              | 15 +++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 mysql-test/main/mdev-38792.result
 create mode 100644 mysql-test/main/mdev-38792.test

diff --git a/mysql-test/main/mdev-38792.result b/mysql-test/main/mdev-38792.result
new file mode 100644
index 0000000000000..31e07d8cd1223
--- /dev/null
+++ b/mysql-test/main/mdev-38792.result
@@ -0,0 +1,10 @@
+SET sql_mode = 'ORACLE';
+SELECT TO_DATE('2002 AD', 'YYYY - AD') FROM DUAL;
+TO_DATE('2002 AD', 'YYYY - AD')
+2002-03-15 00:00:00
+SELECT TO_DATE('2002 - AD', 'YYYY AD') FROM DUAL;
+TO_DATE('2002 - AD', 'YYYY AD')
+2002-03-15 00:00:00
+SELECT TO_DATE('2002 - AD', 'YYYY-AD') FROM DUAL;
+TO_DATE('2002 - AD', 'YYYY-AD')
+2002-03-15 00:00:00
diff --git a/mysql-test/main/mdev-38792.test b/mysql-test/main/mdev-38792.test
new file mode 100644
index 0000000000000..0396c4baec7ba
--- /dev/null
+++ b/mysql-test/main/mdev-38792.test
@@ -0,0 +1,11 @@
+# TO_DATE: Inconsistent treatment of different separators in the date and format strings
+SET sql_mode = 'ORACLE';
+
+# case 1:
+SELECT TO_DATE('2002 AD', 'YYYY - AD') FROM DUAL;
+
+# case 2: The fixed bug:
+SELECT TO_DATE('2002 - AD', 'YYYY AD') FROM DUAL;
+
+# case 3:
+SELECT TO_DATE('2002 - AD', 'YYYY-AD') FROM DUAL;
diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index c008c2089ba29..b3e9e42a8564e 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -721,6 +721,21 @@ extract_oracle_date_time(THD *thd, uint16 *format_ptr,
       continue;
     }
 
+    /*
+      MDEV-38792: TO_DATE: Inconsistent treatment of different separators in the date and format strings.
+      Skip punctuation and spaces in the input string before matching the next
+      format token, but avoid skipping a '-' sign if it's followed by a digit
+      (as it might be part of a negative year in SYYYY).
+    */
+    while (val < val_end && !my_isalnum(val_cs, *val))
+    {
+      if (*val == '-' && (val + 1 < val_end) && my_isdigit(val_cs, *(val + 1)))
+      {
+        break;
+      }
+      val++;
+    }
+
     error= 0;
     if (!(val_len= (uint) (val_end - val)))
       goto error;