There are a lot of indicators in the MIMIC database that need to be calculated based on time, and time-related indicators need to be calculated through the official time function.
The following table describes the time calculation functions commonly used in the MIMIC database.
If you want to use the datepart parameter in days, replace it with the datepart parameter'day'
The result is preserved to two decimal places.
The result retains an integer.
How to write this sql** if it is written in python?
We still use SQL to find it out directly, but replace the n**icat display with python and print it out.
Let's simplify the SQL, only check the data, and leave the grouping to python
Note***Scientific research included], Reply"Group number of hospital admissions SQL", get sql**.
], Reply"Histogram"to get python.
Construct a histogram of equal width where the histogram range is divided into intervals (buckets) of the same size, and the bucket number to which the value of the expression belongs is returned after evaluation. The function returns an integer value or null if any input is null.
Also, values below the low bucket return 0
Values higher than the high bucket return bucket count +1
Returns an integer value.
Width bucket divides the dataset into buckets of equal width. For example, age 80. This is called a monospaced histogram.
When using width buckets, be aware of the minimum and maximum boundary values. Each bucket contains a value equal to or greater than the base value of that bucket, so an age range such as -40 is effectively 0-1999 and 20-39999。
The width bucket accepts the following data types: (float and or integer), (timestamp and or date and or timestamptz), or (interval and or timetime).
A histogram is an important statistic in a database that describes the distribution of data in a column.
Equi-width histogram divides the interval between the largest and smaller values of the data into n parts, and the difference between the maximum and small values in each bucket is the difference between the maximum and small values of the overall data n, which is the so-called "equal width". Let's take n=20 as an example, and we can get the following results on randomly generated data from this curve:
The biggest flaw of equi-width histogram is that the statistics in buckets with high data frequency are not clear enough, for example, in buckets [55, 60], we only know that its total frequency is 40, but we don't know whether it occurs 8 times each, or 55 occurs 36 times and all other values only once. Therefore, when the number of buckets is much smaller than the number of distinct values in a column, and when there are too many distinct values in a single bucket and are unevenly distributed, there is a high chance that the equi-width histogram will make incorrect estimates and affect the optimization results.
2.1 Example: Extraction of laboratory indicators within 24 hours of a patient's admission to the ICU
Note: The indicators collected 6 hours before entering the ICU and within 24 hours after entering the ICU are all indicators collected within 24 hours.
Use the DateTime Sub function to subtract 6 hours from the time it takes to enter the ICU.
Use the datetime add function to add 24 hours to the ICU entry time.
A time range is obtained, and finally through this time range, it is judged whether the collection time of laboratory indicators can be extracted within 24 hours of entering and exiting the ICU within this time range.
Included in the collection MIMIC database 14PreviousMIMIC Data Extraction Tutorial - How to Extract Surgical Patient Information.