MDEV-13916 Enforce check constraint on JSON type

When creating a field of type JSON, it will be automatically
converted to TEXT with CHECK (json_valid(`a`)), if there wasn't any
previous check for the column.

Additional things:
- Added two bug fixes that was found while testing JSON. These bug
  fixes has also been pushed to 10.3 (with a test case), but as they
  where minimal and needed to get this task done and tested, the fixes
  are repeated here.
  - CREATE TABLE ... SELECT drops constraints for columns that
    are both in the create and select part.
  - If one has both a default expression and check constraint for a
    column, one can get the error "Expression for field `a` is refering
    to uninitialized field `a`.
- Removed some duplicate MYSQL_PLUGIN_IMPORT symbols

1 files changed, 35 insertions, 0 deletions

diff --git a/mysql-test/main/type_json.test b/mysql-test/main/type_json.test
index 0cff9366145..bd13dc1fcf4 100644
--- a/mysql-test/main/type_json.test
+++ b/mysql-test/main/type_json.test
@@ -17,12 +17,47 @@ insert t1 values ('[]');
 --error ER_CONSTRAINT_FAILED
 insert t1 values ('a');
 
+create or replace table t1(a json not null);
+show create table t1;
+insert t1 values ('[]');
+--error ER_CONSTRAINT_FAILED
+insert t1 values ('a');
+
 set timestamp=unix_timestamp('2010:11:12 13:14:15');
 create or replace table t1(a json default(json_object('now', now())));
 show create table t1;
 insert t1 values ();
 select * from t1;
+drop table t1;
+
+create table t1 (t json) as select json_quote('foo') as t;
+create table t2 (a json) as select json_quote('foo') as t;
+create table t3 like t1;
+select * from t1;
+show create table t1;
+show create table t2;
+show create table t3;
+drop table t1,t2,t3;
 
+create table t1 (t json check (length(t) > 0));
+show create table t1;
+drop table t1;
+
+create table t1 (t text) engine=myisam;
+insert into t1 values ("{}"),("");
+--error ER_CONSTRAINT_FAILED
+create table t2 (t json) select t from t1;
+--error ER_NO_SUCH_TABLE
+select * from t2;
+drop table t1;
+
+create or replace table t1(a json default(json_object('now', 1)) check (json_valid(a)));
+insert into t1 values ();
+insert into t1 values ("{}");
+--error ER_CONSTRAINT_FAILED
+insert into t1 values ("xxx");
+select * from t1;
+show create table t1;
 drop table t1;
 
 --error ER_PARSE_ERROR