Temporal Intervals { identifier expr }  is ODBC escape syntax and is accepted for ODBC compatibility. The value is expr . The  {  and  }  curly braces in the syntax should be written literally; they are not metasyntax as used elsewhere in syntax descriptions. match_expr  indicates a  MATCH  expression. See Section 12.10, “Full-Text Search Functions” . case_expr  indicates a  CASE  expression. See Section 12.5, “Flow Control Functions” . interval_expr  represents a temporal interval. See Temporal Intervals. Temporal Intervals interval_expr  in expressions represents a temporal interval. Intervals have this syntax: INTERVAL  expr unit expr  represents a quantity.  unit  represents the unit for interpreting the quantity; it is a specifier such as HOUR ,  DAY , or  WEEK . The  INTERVAL  keyword and the  unit  specifier are not case-sensitive. The following table shows the expected form of the  expr  argument for each  unit  value. Table 9.2 Temporal Interval Expression and Unit Arguments unit  Value Expected  expr  Format MICROSECOND MICROSECONDS SECOND SECONDS MINUTE MINUTES HOUR HOURS DAY DAYS WEEK WEEKS MONTH MONTHS QUARTER QUARTERS YEAR YEARS SECOND_MICROSECOND ’SECONDS.MICROSECONDS’ MINUTE_MICROSECOND ’MINUTES:SECONDS.MICROSECONDS’ MINUTE_SECOND ’MINUTES:SECONDS’ HOUR_MICROSECOND ’HOURS:MINUTES:SECONDS.MICROSECONDS’ HOUR_SECOND ’HOURS:MINUTES:SECONDS’ HOUR_MINUTE ’HOURS:MINUTES’ DAY_MICROSECOND ’DAYS HOURS:MINUTES:SECONDS.MICROSECONDS’ DAY_SECOND ’DAYS HOURS:MINUTES:SECONDS’ DAY_MINUTE ’DAYS HOURS:MINUTES’ DAY_HOUR ’DAYS HOURS’ YEAR_MONTH ’YEARS-MONTHS’ MySQL permits any punctuation delimiter in the  expr  format. Those shown in the table are the suggested delimiters. 1917