user: Question: What is the date of injury when the injury is Sustained posterior thigh strains in his left leg?
Columns: ['Date', 'Player', 'Injury', 'Date of injury', 'Number of matches (Total)', 'Source']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['August 4, 2010', 'Davide Santon', 'Clean-up surgery on his right knee', 'April 7, 2010', '12', 'inter.it']
SQL:

assistant: SELECT "Date of injury" FROM "Table" WHERE "Injury" = 'Sustained posterior thigh strains in his left leg';