The simplest and best way to get yesterday’s date is subdate:
subdate(current_date, 1)
Your query would be:
SELECT
url as LINK,
count(*) as timesExisted,
sum(DateVisited between UNIX_TIMESTAMP(subdate(current_date, 1)) and
UNIX_TIMESTAMP(current_date)) as timesVisitedYesterday
FROM mytable
GROUP BY 1
For the curious, the reason that sum(condition)
gives you the count of rows that satisfy the condition, which would otherwise require a cumbersome and wordy case
statement, is that in mysql boolean values are 1
for true and 0
for false, so summing a condition effectively counts how many times it’s true. Using this pattern can neaten up your SQL code.