When was the start of the construction of the unit that's been in commercial operation since 04.03.1987?
CREATE TABLE table_12983929_1 (construction_start VARCHAR, commercial_operation VARCHAR)
SELECT construction_start FROM table_12983929_1 WHERE commercial_operation = "04.03.1987"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_12983929_1 (construction_start VARCHAR, commercial_operation VARCHAR) Question: When was the start of the construction of the unit that's been in commercial operation since 04.03.1987? [/INST] SELECT construction_start FROM table_12983929_1 WHERE commercial_operation = "04.03.1987" </s>