selecting a column from multiple tables in mysql - mysql

Question

TABLE 1
+----+-------+-------+-------+
| uid | color | brand | model |
+----+-------+-------+-------+
| 10 | 1 | 2 | 1 |
+----+-------+-------+-------+
TABLE 2
+----+-------+-------+-------+
| uid | quantity |model |color|
+----+-------+-------+-------+
| 25 | 2 | 2 | 1 |
+----+-------+-------+-------+
I have many tables like this where the uid column is present in every table.I have a value in a variable, say var1=25. I want to check whether var1 value matches with any of the uid value of any table.If it matches I want to print the table name. Can anyone help me with this?
I tried doing this and I found
SELECT `COLUMN_NAME`
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename'
AND `TABLE_NAME`='yourtablename';
But this is not giving what I want since I want to select all the tables in a database irrespective of the table name.If in future any table is added then it should also get selected.

Answer 1

At first, information_schema table doesn't have specific tuple data.
I suggest you to consider different design.
A. Make a meta table and use triggers(attached to base tables) to maintain meta table.
CREATE TABLE meta_table (
id INT AUTO_INCREMENT,
uid INT,
table_name VARCHAR(50)
);
# When you need to add new table (table 3)
CREATE TABLE table_3 (
uid INT,
field1 INT,
field2 INT,
field3
);
DELIMITER $$
CREATE TRIGGER table_3_insert
AFTER INSERT ON table_3
FOR EACH ROW
BEGIN
INSERT INTO meta_table (uid, table_name)
VALUE (NEW.uid, "table_3");
END$$
DELIMITER ;
# If data in `table_3` might be changed or deleted,
# then create trigger for `delete` and `update`
B. Use only one table with unstructured field and parse data field in your application
CREATE TABLE table (
uid INT,
table_type INT,
data VARCHAR(255)
);
INSERT INTO table (10, 1, '{"color":1,"brand":2,"model":1}');
INSERT INTO table (10, 2, '{"quantity":2,"model":2,"color":1}');
As you mentioned "any table can be added" often, I strongly recommend B solution. It is not good design that changing schema(creating table) often.