Single quotation marks and double quotation marks in SQL statements

In SQL databases, it is often difficult to figure out whether to write single quotes or double quotes when writing some statements. After some queries, I agree with the following. Here, the string type is used as an example:

When I have a table named studentname, there is a field named

I want to insert a name named "Zhang San" into it, so

Strtxtsql = "insert into studentname (name) value ('zhang san ')"

Because it is a string, single quotation marks must be placed on both sides of the insert statement. If "Michael" is replaced with a variable A, the statement is:

Strtxtsql = "insert into studentname (name) value ('" & &"')"

Here, if variable A is to replace Michael, it needs to be "& A &", which requires a connector and double quotation marks. In comparison with the above sentence, double quotation marks are used to include variables, A single quotation mark is a value that contains a field.

Here is just a comment on the string quotation marks. Of course, different types are also different, so you must note when writing.