Loop through JSON array in PLSQL 12.1 - sql

Question

I have JSON array inside varchar
DECLARE
JsonArray varchar2(1000);
arrayCars varchar2(1000);
BEGIN
JsonArray :={"Cars": [{"name":"Honda", "color":"red" },
{"name":"Toyota", "color":"green"}] }
SELECT JSON_QUERY(JsonArray, '$.Cars') into arrayCars FROM dual;
END;
/
Now if I print out arrayCars i will get
[{"name":"Honda","color":"red"},{"name":"Toyota","color":"green"}]
But how can I loop through this Cars array and print out it's components seperately (get access to them)?

Answer 1

You can directly use SQL with JSON_TABLE() function which is available starting with Oracle DB 12.1.0.2 version such as
WITH t(arrayCars) AS
(
SELECT JSON_QUERY('{"Cars": [{"name":"Honda", "color":"red" },
{"name":"Toyota", "color":"green"}] }', '$.Cars')
FROM dual
)
SELECT name, color
FROM t
CROSS JOIN JSON_TABLE(arrayCars,
'$' COLUMNS(NESTED PATH '$[*]'
COLUMNS(
name VARCHAR2(100) PATH '$.name',
color VARCHAR2(100) PATH '$.color'
)
)
);
Demo
If you really need to use PL/SQL, then consider creating a function with SYS_REFCURSOR return type such as
CREATE OR REPLACE FUNCTION Get_Cars RETURN SYS_REFCURSOR IS
v_recordset SYS_REFCURSOR;
JsonArray VARCHAR2(1000);
arrayCars VARCHAR2(1000);
v_sql VARCHAR2(32767);
BEGIN
JsonArray :='{"Cars": [{"name":"Honda", "color":"red" },
{"name":"Toyota", "color":"green"}] }';
arrayCars := JSON_QUERY(JsonArray, '$.Cars');
DBMS_OUTPUT.PUT_LINE(arrayCars);
v_sql :=
'SELECT name,color
FROM dual
CROSS JOIN JSON_TABLE(:Cars,
''$'' COLUMNS(NESTED PATH ''$[*]''
COLUMNS(
name VARCHAR2(100) PATH ''$.name'',
color VARCHAR2(100) PATH ''$.color''
)
)
)';
OPEN v_recordset FOR v_sql USING arrayCars;
RETURN v_recordset;
END;
/
and then call from SQL Developer's console as
SQL> DECLARE
result SYS_REFCURSOR;
BEGIN
:result := Get_Cars;
END;
/
SQL> PRINT result ;
Edit(for your last comment):
Alternatively, you can use a simple implicit loop such as
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
v_name VARCHAR2(1000);
v_color VARCHAR2(1000);
BEGIN
FOR c IN (
SELECT name,color
FROM JSON_TABLE('{"Cars": [{"name":"Honda", "color":"red" },
{"name":"Toyota", "color":"green"}] }',
'$' COLUMNS(NESTED PATH '$.Cars[*]'
COLUMNS(
name VARCHAR2(100) PATH '$.name',
color VARCHAR2(100) PATH '$.color'
)
)
)
)
LOOP
v_name := c.name;
v_color := c.color;
DBMS_OUTPUT.PUT_LINE(v_name||' '||v_color);
END LOOP;
END;
/
Demo2