通用SQL问题

SELECT column1, column2 FROM table_name;

SELECT * FROM table_name;

SELECT column1, column2 FROM table_name WHERE condition;

SELECT column1, column2 FROM table_name ORDER BY column1 ASC;

SELECT column1, COUNT(*) FROM table_name GROUP BY column1;

SELECT COUNT(*), SUM(column1), AVG(column2) FROM table_name;

SELECT table1.column1, table2.column2 FROM table1 JOIN table2 ON table1.column1 = table2.column1;

INSERT INTO table_name (column1, column2) VALUES ('value1', 'value2');

UPDATE table_name SET column1 = 'value1' WHERE condition;

DELETE FROM table_name WHERE condition;

CREATE TABLE table_name (
    column1 datatype PRIMARY KEY,
    column2 datatype
);

CREATE TABLE table_name (
    column1 datatype PRIMARY KEY,
    column2 datatype,
    FOREIGN KEY (column2) REFERENCES other_table(column_name)
);

CREATE TABLE table_name (
    column1 datatype UNIQUE,
    column2 datatype
);

CREATE TABLE table_name (
    column1 datatype NOT NULL,
    column2 datatype
);

CREATE TABLE table_name (
    column1 datatype DEFAULT value,
    column2 datatype
);

CREATE INDEX index_name ON table_name (column1);

EXPLAIN SELECT column1, column2 FROM table_name WHERE condition;