What is the correct syntax to write "merge statement" in PostgreSQL 9.6.2 - postgresql

Question

code :It is merge query which is running on Postgres 9.6.2 and giving syntax error.
<<!--It is giving syntax error--->
MERGE INTO timesheets.timesheet_report AS tgt USING timesheets.tmp_timesheet_report AS src ON src.FMNo = tgt.FMNo
AND src.ts_start_dt = tgt.ts_start_dt
AND src.charge_code = tgt.charge_code WHEN NOT MATCHED
INSERT (tgt.FIRST_NAME,
tgt.LAST_NAME)
VALUES(src.FIRST_NAME,
src.LAST_NAME) WHEN MATCHED
UPDATE
SET tgt.FIRST_NAME = src.FIRST_NAME,
tgt.LAST_NAME = src.LAST_NAME;

Answer 1

It is ON CONFLICT
INSERT INTO table_name [your usual insert syntax here]
ON CONFLICT [some conflict definition]
DO UPDATE SET column1 = EXCLUDED.value1
So I guess your query would look like this:
INSERT INTO timesheets.timesheet_report (FMNo, ts_start_dt, charge_code, FIRST_NAME, LAST_NAME)
SELECT src.FMNo, src.ts_start_dt, src.charge_code, src.FIRST_NAME, src.LAST_NAME FROM timesheets.tmp_timesheet_report AS src
ON CONFLICT (FMNo, ts_start_dt, charge_code)
DO UPDATE
SET FIRST_NAME = EXCLUDED.FIRST_NAME,
LAST_NAME = EXCLUDED.LAST_NAME;
If you don't have primary key or unique index, then you need to create unique index on timesheets.timesheet_report using btree (FMNo, ts_start_dt, charge_code);