add some useful queries

docs/examples/queries.md

@@ -1,13 +1,103 @@
 # Useful Queries
 
-## Cone search around a coordinate
+## Targets
 
-You can search for targets within a certain radius from a give coordinate by using Q3C.
+### Around a coordinate
 
 ```sql
 /* Select 10 objects within r=1 deg from the center of
    the COSMOS region (RA=150, Dec=2) */
 SELECT * FROM target
-    WHERE q3c_radial_query(ra, dec, 150.0, 2.0, 1.0)
-    LIMIT 10;
+WHERE q3c_radial_query(ra, dec, 150.0, 2.0, 1.0)
+LIMIT 10;
+```
+
+### For single proposal
+
+```sql
+/* Select all rows from the target table where the proposal_id is
+   'S25A-058QN' */
+SELECT *
+FROM target
+WHERE proposal_id = 'S25A-058QN';
+```
+
+### For multiple proposals
+
+```sql
+/* Select all rows from the target table where the proposal_id is
+   'S25A-058QN' or 'S25A-028QN' */
+SELECT *
+FROM target
+WHERE proposal_id IN ('S25A-058QN', 'S25A-028QN');
+```
+
+### For proposals with a semester prefix
+
+```sql
+/* Select all rows from the target table where the proposal_id starts
+   with 'S25A' */
+SELECT *
+FROM target
+WHERE proposal_id LIKE 'S25A%';
+```
+
+### For a semester with the `active` flag is `true`
+
+```sql
+/* Select all rows from the target table where the proposal_id starts
+   with 'S25A' and the input catalog is active */
+SELECT t.*
+FROM target t
+JOIN input_catalog ic ON t.input_catalog_id = ic.input_catalog_id
+WHERE t.proposal_id LIKE 'S25A%'
+AND ic.active = TRUE;
+```
+
+### With user-defined custom pointings
+
+#### Select all user-defined custom pointings for classical proposals
+
+```sql
+/* Select all rows from the user_pointing table for proposals asking
+    classical observation with user pointing */
+SELECT up.*
+FROM user_pointing up
+JOIN input_catalog ic ON up.input_catalog_id = ic.input_catalog_id
+WHERE ic.is_user_pointing = TRUE
+AND ic.is_classical = TRUE;
+```
+
+#### Select targets for a classical proposal requesting user pointing
+
+```sql
+/* Select all targets for a classical proposal requesting user pointing */
+SELECT t.target_id, t.obj_id, t.ra, t.dec, t.proposal_id, t.input_catalog_id
+FROM target t
+JOIN input_catalog ic ON t.input_catalog_id = ic.input_catalog_id
+WHERE t.proposal_id = 'S25A-039'
+AND ic.active = TRUE
+AND ic.is_classical = TRUE
+AND ic.is_user_pointing = TRUE;
+```
+
+#### Select custom pointing information for a classical proposal requesting user pointing
+
+The query is useful to fetch data for a classical proposal requesting user pointing by using only the `proposal_id`.
+
+```sql
+/* Select all user pointing information for a classical proposal requesting user pointing */
+SELECT up.user_pointing_id, up.ppc_code, up.ppc_ra, up.ppc_dec, up.ppc_pa,
+       up.ppc_resolution, up.ppc_priority, up.input_catalog_id
+FROM user_pointing up
+JOIN input_catalog ic ON up.input_catalog_id = ic.input_catalog_id
+WHERE ic.active = TRUE
+AND ic.is_classical = TRUE
+AND ic.is_user_pointing = TRUE
+AND EXISTS (
+    SELECT 1
+    FROM target t
+    WHERE t.input_catalog_id = ic.input_catalog_id
+    AND t.proposal_id = 'S25A-039'
+);
 ```