SQL query, significant digits of the float type

select cast( as decimal(15,2))

The results can be swapped out for your fields.

SQL 2005 database.

Use this method.

select cast( as numeric(10,2));

This method works. I just interviewed in SQL 2005.

Convert the area to a character type, and then use the truncation function to"."The boundary is truncated into 2 parts, the first part is not edged, and the following part is rounded by a function.

round function.

Syntax: round ( numeric expression , length [ function ].)

Example. select round(,-1)

The 1st place to the left of the decimal point is rounded to 0

select round(,-2)

The 2nd digit to the left of the decimal point is rounded to 0 digits

select round(,-3)

The 3rd digit to the left of the decimal point is rounded to 0 digits

select round(,2)

Rounding is the number of decimal places specified in length.

select round(,3)

Rounding is the number of decimal places specified in length.

select round(,3)

Rounding is the number of decimal places specified in length.

cast(as decimal(m,n)).

The Decimal accuracy is higher than that of Float, and there is no problem with the conversion.

float(n) is a floating-point number that stores an approximation, where the parameter n determines the precision. The maximum value of n is 53, and when n takes 53, the storage range is +308 to and -308 to +308.

When the value of n is 24, it is real. That is, real=float(24). At this point, the storage range is +38 to and - 38 to +38.

There is also numeric (equivalent to decimal), which stores exact values.

The solution and operation steps are as follows:

1. First of all, open the SQL Server database, and then prepare a decimal place, see the figure below.

2. Secondly, after completing the above steps, you can use the round function for decimal processing, but round will change the decimal to 0 instead of keeping the actual number of digits, see the figure below.

3. Then, you can use the cast function to perform a decimal conversion to a numeric type, as shown in the figure below.

4. However, when using cast, it is important to note that the conversion type does not cause digital overflow, see the figure below.

5. Then, when writing the transformation, you should write the number of bits of the type of transformation as large as possible, as shown in the figure below.

6. Finally, you can also use the convert function to convert, which is similar to the cast usage, see the figure below.

1. First of all, we open the SQL Server database, and then prepare a decimal as shown in the figure below.

2. Then we can use the round function to process the decimal number, but the round will turn the decimal into 0 instead of the real number of reserved digits.

3. Next, we can use the cast function to convert the decimal to the numeric type, as shown in the figure below.

4. However, when using cast, it should be noted that the number of bits overflow should not occur in the type of conversion, as shown in the figure below.

5. When we convert, we should write as much as possible the number of bits of the type of conversion, as shown in the figure below.

6. Then you can also convert it through the convert function, as shown in the figure below, which is similar to the cast usage.

Here's how to control the number of decimal places:

decimal(18,0)

18 is the fixed-point precision and 0 is the number of decimal places.

decimal(a,b)

aSpecify the maximum number of decimal digits that can be stored to the left and right of the specified decimal point, with a maximum precision of 38.

bSpecifies the maximum number of decimal digits that can be stored to the right of the decimal point. The number of decimal places must be a value between 0 and a. The default number of decimal places is 0.

Examples: decimal[ (p[ ,s]) and numeric[ (p[ ,s]).

Fixed precision and number of decimal places. When using maximum precision, the ISO synonyms of valid values from - 10 38 +1 to 10 38 - are dec and dec(p, s), and numeric is functionally equivalent to decimal.

p (precision) The maximum number of digits of a decimal digit that can be stored, including the number of digits to the left and right of the decimal point.

The precision must be a value between 1 and a maximum precision of 38. The default precision is 18.

s (number of decimal places).

The maximum number of decimal places that can be stored to the right of the decimal point, which must be a value between 0 and p.

You can specify the number of decimal places only after specifying the precision, and the default number of decimal places is 0;

Therefore, 0 < = s < = p. The maximum storage size varies based on precision.

Not showing the leading 0 is not a problem of the data itself, it needs to be formatted in the displayed program with a function such as formatnumber.

No, you can use numeric or decimal to convert, how can it appear. 95 data yet.

In SQLSer, real is a 16-bit floating-point type, and float is a 32-bit float, which is different from C's.

The real and float in sqlserver correspond to the float and double in c, respectively

real is a 4-byte 32-bit floating-point.

float is an 8-byte, 64-bit floating-point.

nu what begins with... You need to specify the width.

Write a constraint alter table table name sell early add constraint ck aa check (listed) in teasing finch = 0 and column name <=100) to refer to respect.

Floating-point data type.

The floating-point data type is used to store decimal decimals. Data with floating-point values is stored in SQL Server using round up or round-up. Rounding up means that if (and only if) the number to be rounded is a non-zero number, add 1 to the value in the least significant place of the part of the reserved digit and carry the necessary rounding.

If a number is rounded, its absolute value is not reduced. For example, if you round 2 and 12 digits to , the result is and .

1. The real data type.

The real data type can be accurate to the 7th decimal place and can range from -38 to +38. Each real type of data occupies 4 bytes of storage space.

2、float

The float data type can be accurate to the 15th decimal place, and it can range from -308 to +308. Each float type of data occupies 8 bytes of storage space. The float data type can be written as float[ n ].

n specifies the precision of the float data. n is an integer value between 1 and 15. When n takes 1 to 7, it actually defines a real type of data, and the system stores it in 4 bytes; When n takes 8 to 15, the system thinks it is of type float and stores it in 8 bytes.

3、decimal

The decimal data type can provide the actual storage space required for decimals, but there is a limitation, you can use 2 to 17 bytes to store values from -10 to the power of -1 to the power of 10 to the power of 38 -1. It can be written in the form of decimal [ p [ s ] ], p and s determine the exact proportions and digits. where p is the total number of digits (excluding decimal points) of the value that can be stored, and the default value is 18; s represents the number of digits after the decimal point, and the default value is 0.

For example: decimal (15 5), which means that there are 15 digits, where the whole number is 10 digits and the decimal is 5. Bittable 4-3 lists the relationship between the number of bytes required for each accuracy.

4、numeric

The numeric data type is exactly the same as the decimal data type.

Note: In order to work with the front-end development tools, SQL Server supports a maximum data precision of 28 bits by default.

Basically, there is no difference, they all represent decimals, but their width is different, or the precision is different, float is single precision, double is double precision, they represent the range of decimal places, double can represent the range, larger than float, double in memory, accounting for 8 bytes, float accounts for 4 bytes, the relationship between float and double is like the relationship between short and long.