Which SQL function call returns the same result as LEFT(text_field, 1)?

Which SQL function call returns the same result as LEFT(text_field, 1)?

• A. SUBSTRING(text_field, 1, 1)
• B. SUBSTRING(text_field, 0, 1)
• C. SUBSTRING(text_field, 1, 0)
• D. SUBSTRING(text_field, 2, 1)

Answer: (A)

The function call that matches the result of LEFT(text_field, 1) is indeed SUBSTRING(text_field, 1, 1). The LEFT function extracts a specified number of characters from the start of a text string, so LEFT(text_field, 1) retrieves the first character of the string in text_field. The equivalent SQL function, SUBSTRING, operates with a slightly different logic: it takes three parameters – the source string, the starting position, and the length of the substring. By calling SUBSTRING(text_field, 1, 1), you are instructing the database to start at position 1 (the first character) and return 1 character, which effectively gives you the same result as using LEFT(text_field, 1). The other answer choices do not provide the same outcome because they either reference incorrect starting positions or lengths, which would not yield the first character of the string. Using a starting position of 0 or asking for a length of 0 does not access or return any valid characters from the input text. Therefore, the choice of SUBSTRING(text_field, 1, 1) accurately mimics the functionality of LEFT when extracting just the first character from a string.

The function call that matches the result of LEFT(text_field, 1) is indeed SUBSTRING(text_field, 1, 1).

The LEFT function extracts a specified number of characters from the start of a text string, so LEFT(text_field, 1) retrieves the first character of the string in text_field. The equivalent SQL function, SUBSTRING, operates with a slightly different logic: it takes three parameters – the source string, the starting position, and the length of the substring. By calling SUBSTRING(text_field, 1, 1), you are instructing the database to start at position 1 (the first character) and return 1 character, which effectively gives you the same result as using LEFT(text_field, 1).

The other answer choices do not provide the same outcome because they either reference incorrect starting positions or lengths, which would not yield the first character of the string. Using a starting position of 0 or asking for a length of 0 does not access or return any valid characters from the input text. Therefore, the choice of SUBSTRING(text_field, 1, 1) accurately mimics the functionality of LEFT when extracting just the first character from a string.