The database queries the maximum value for each field

SQL stands for Structured Query Language.

structured query language), which is a special-purpose programming language.

is a database query and programming language.

for accessing data and querying, updating, and managing relational database systems;

SQL statement, to get the maximum value of a field, you can use the max()max function to return the maximum value in a column. null values are not included in the calculation.

sql max() syntax:

select max(column_name) from table_name

Note: max can also be used in text columns to get the highest or lowest value in alphabetical order.

The select statement is used to pick up data from a table. The results are stored in a results table (called a result set).

Data content: <>

Result: <>

This is the source data for the table:

sql:select date(a.`times`),a.`name`,min(a.`times`),max(a.`times`)from test1 a

group by date(a.`times`),a.`name`;

Group by date, name, find the minimum and maximum values.

1. The initial clock-in time.

select n, min(d) from t group by n;

1. The last time to punch in.

select n, max(d) from t group by n;

The maximum value of a SQL query field uses the max() function.

Example: select

max(a)

fromtable

The gist of the statement is to retrieve the maximum value in the A field of the table.

Just use where to set two intervals, I write the date format may not be right, you can adjust it yourself.

select id,riqi,shijian from kq where >date(18:00:00) or

select id,riqi,min(shijian),max(shijian) from kq k group by id ,riqi

If you don't want noon, you can add another query condition.

select id,riqi,min(shijian),max(shijian) from kq where riqi>'...' or riqi<'...' k group by id

It's best if there is a unique number in your table. If not, you can add a field to the table called aid auto-increment and the primary key.

Then you can start selecting the first record with the same ID.

For example, if the table name is tmptable, it has:

The first solution:

You can choose to use the grouping function, that is, group by, then all columns except id, you need to use aggregate functions for them, such as maxmax, minmin, count to calculate the number of rows, etc., the example of the statement:

select id, max (any column), min (any column), count (any column).

from table

Note: You can add a where condition here to filter your data.

group by id

The second is to sort according to a certain column, and use row number() to filter the data, for example.

select aa.*

fromselect a.*,row number() over(partition by order by column you need to sort) n1

from table a )aa

where

This is the most basic function.

select max(field name) from table name.

There are two ways to do it.

Only this field is displayed.

select

max (column name).

fromTable name; Displays all fields of the record.

select

top1from

The table name is order

by Listing. desc

For example, you can write the following for querying records whose time field is between 2008-01-01 and 2008-10-31

select * from table name where time field between'2008-01-01' and '2008-12-31'

Or select * from the table name where the time field >='2008-01-01'and time field <='2008-12-31'

If you query all data less than 2008-10-31 (inclusive), that is:

select * from table name where time field <='2008-12-31'

1. First, we open our computer, and then we open the minitab on our computer.

2. After that, we click on the file in the upper left corner.

3. Then we click on Options.

4. After that, we click on the object designer.

5. Then we click on the click check box below the query design to output all fields.

7. Finally, we can click OK, so that we can open the output of all fields in the query design.

select * from table name where field name > maxvalue or field name < minvalue

That's what it means.

Query all records that are greater than the maxvalue value or smaller than the minvalue value.