SQL statements in mysql databases

SQL statements in the mysql database! Query statement: select * from table name where condition. what does this mean? however, select * from database name. & quot;. $ NowItemData. & quot; where condition! There is no SQL statement in the database. mysql database!
Query statement:
Select * from table name where condition;
I know what this means;
However, select * from database name. ". $ NowItemData." where condition!
No. ". $ NowItemData." table in the database
What does this mean!

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$ NowItemData is a php variable. you can find it by echo.
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. $ NowItemData: it is a variable and the content should be a table name.