Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_17903 ( "Unit" text, "Type" text, "Net power" text, "Total power" text, "Construction start" text, "Construction finish" text, "Commercial operation" text, "Shut down" text )

### Question ###
When was the start of the construction of the unit that's been in commercial operation since 04.03.1987?

### Accurate SQL ###

SELECT "Construction start" FROM table_17903 WHERE "Commercial operation" = '04.03.1987'