我现在有两个表，可以用id关联，表t1的x列存的是int类型的值，表t2的x列存的是string类型的值，我现在想用dolphindb中的unionAll函数将两个表合成一个表，我尝试了以下两种写法都不行：
t1=table(1 2 3 as id, 11 12 13 as x)
t2=table(3 4 5 as id, `a`b`c as x)
unionAll(t1,t2);
/*错误：
unionAll(t1, t2) => Failed to append data to column 'x'
*/
t1=table(1 2 3 as id, 11 12 13 as x)
t2=table(3 4 5 as id, `a`b`c as x)
unionAll(t1,t2,true);
/*错误：
unionAll(t1, t2, 1) => The data type of column [x] of the input table [#1] is inconsistent with that of other input tables.
*/
请问应该怎么办？
