How many values of r z(arcsecond) are associated with a target datum of Ireland 1965?
CREATE TABLE table_15318324_1 (r_z___arcsecond__ VARCHAR, target_datum VARCHAR)
SELECT r_z___arcsecond__ FROM table_15318324_1 WHERE target_datum = "Ireland 1965"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_15318324_1 (r_z___arcsecond__ VARCHAR, target_datum VARCHAR) Question: How many values of r z(arcsecond) are associated with a target datum of Ireland 1965? [/INST] SELECT r_z___arcsecond__ FROM table_15318324_1 WHERE target_datum = "Ireland 1965" </s>