Patch for BUG#30736: Row Size Too Large Error Creating a Table and

Inserting Data.

The problem was that under some circumstances Field class was not
properly initialized before calling create_length_to_internal_length()
function, which led to assert failure.

The fix is to do the proper initialization.

The user-visible problem was that under some circumstances
CREATE TABLE ... SELECT statement crashed the server or led
to wrong error message (wrong results).

mysql-test/r/select.result

@@ -4096,4 +4096,39 @@ SELECT `x` FROM v3;
 x
 1
 DROP VIEW v1, v2, v3;
+
+#
+# Bug#30736: Row Size Too Large Error Creating a Table and
+# Inserting Data.
+#
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+
+CREATE TABLE t1(
+c1 DECIMAL(10, 2),
+c2 FLOAT);
+
+INSERT INTO t1 VALUES (0, 1), (2, 3), (4, 5);
+
+CREATE TABLE t2(
+c3 DECIMAL(10, 2))
+SELECT
+c1 * c2 AS c3
+FROM t1;
+
+SELECT * FROM t1;
+c1	c2
+0.00	1
+2.00	3
+4.00	5
+
+SELECT * FROM t2;
+c3
+0.00
+6.00
+20.00
+
+DROP TABLE t1;
+DROP TABLE t2;
+
 End of 5.0 tests

mysql-test/t/select.test

@@ -3484,4 +3484,52 @@ DROP VIEW v1, v2, v3;
 
 --enable_ps_protocol
 
+###########################################################################
+
+--echo
+--echo #
+--echo # Bug#30736: Row Size Too Large Error Creating a Table and
+--echo # Inserting Data.
+--echo #
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+--enable_warnings
+
+--echo
+
+CREATE TABLE t1(
+  c1 DECIMAL(10, 2),
+  c2 FLOAT);
+
+--echo
+
+INSERT INTO t1 VALUES (0, 1), (2, 3), (4, 5);
+
+--echo
+
+CREATE TABLE t2(
+  c3 DECIMAL(10, 2))
+  SELECT
+    c1 * c2 AS c3
+  FROM t1;
+
+--echo
+
+SELECT * FROM t1;
+
+--echo
+
+SELECT * FROM t2;
+
+--echo
+
+DROP TABLE t1;
+DROP TABLE t2;
+
+--echo
+
+###########################################################################
+
 --echo End of 5.0 tests

sql/sql_table.cc

@@ -955,8 +955,8 @@ static int mysql_prepare_table(THD *thd, HA_CREATE_INFO *create_info,
 	  sql_field->length=		dup_field->char_length;
           sql_field->pack_length=	dup_field->pack_length;
           sql_field->key_length=	dup_field->key_length;
-	  sql_field->create_length_to_internal_length();
 	  sql_field->decimals=		dup_field->decimals;
+	  sql_field->create_length_to_internal_length();
 	  sql_field->unireg_check=	dup_field->unireg_check;
           /* 
             We're making one field from two, the result field will have