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Capítulo 23 - Apéndice D: Hoja de trucos SQL
Sintaxis SQL
- Seleccionar todas las columnas de una tabla
SELECT * FROM table_name;- Seleccionar columnas específicas de una tabla
SELECT column1, column2 FROM table_name;- Seleccionar valores distintos de una columna
SELECT DISTINCT column_name FROM table_name;- Contar valores distintos de una columna
SELECT COUNT(DISTINCT column_name) FROM table_name;- Filtrar usando WHERE
SELECT * FROM table_name WHERE column_name = 'value';- Ordenar por columnas
SELECT * FROM table_name ORDER BY column_name ASC|DESC;- Funciones de Agregación
SELECT COUNT(column_name) FROM table_name;
SELECT AVG(column_name) FROM table_name;
SELECT SUM(column_name) FROM table_name;
SELECT MIN(column_name) FROM table_name;
SELECT MAX(column_name) FROM table_name;- Agrupar por columnas
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column;- Cláusula Having (usada con GROUP BY)
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column HAVING COUNT(column_name) > 10;Sintaxis SQL
- Seleccionar todas las columnas de una tabla
SELECT * FROM table_name;- Seleccionar columnas específicas de una tabla
SELECT column1, column2 FROM table_name;- Seleccionar valores distintos de una columna
SELECT DISTINCT column_name FROM table_name;- Contar valores distintos de una columna
SELECT COUNT(DISTINCT column_name) FROM table_name;- Filtrar usando WHERE
SELECT * FROM table_name WHERE column_name = 'value';- Ordenar por columnas
SELECT * FROM table_name ORDER BY column_name ASC|DESC;- Funciones de Agregación
SELECT COUNT(column_name) FROM table_name;
SELECT AVG(column_name) FROM table_name;
SELECT SUM(column_name) FROM table_name;
SELECT MIN(column_name) FROM table_name;
SELECT MAX(column_name) FROM table_name;- Agrupar por columnas
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column;- Cláusula Having (usada con GROUP BY)
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column HAVING COUNT(column_name) > 10;Sintaxis SQL
- Seleccionar todas las columnas de una tabla
SELECT * FROM table_name;- Seleccionar columnas específicas de una tabla
SELECT column1, column2 FROM table_name;- Seleccionar valores distintos de una columna
SELECT DISTINCT column_name FROM table_name;- Contar valores distintos de una columna
SELECT COUNT(DISTINCT column_name) FROM table_name;- Filtrar usando WHERE
SELECT * FROM table_name WHERE column_name = 'value';- Ordenar por columnas
SELECT * FROM table_name ORDER BY column_name ASC|DESC;- Funciones de Agregación
SELECT COUNT(column_name) FROM table_name;
SELECT AVG(column_name) FROM table_name;
SELECT SUM(column_name) FROM table_name;
SELECT MIN(column_name) FROM table_name;
SELECT MAX(column_name) FROM table_name;- Agrupar por columnas
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column;- Cláusula Having (usada con GROUP BY)
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column HAVING COUNT(column_name) > 10;Sintaxis SQL
- Seleccionar todas las columnas de una tabla
SELECT * FROM table_name;- Seleccionar columnas específicas de una tabla
SELECT column1, column2 FROM table_name;- Seleccionar valores distintos de una columna
SELECT DISTINCT column_name FROM table_name;- Contar valores distintos de una columna
SELECT COUNT(DISTINCT column_name) FROM table_name;- Filtrar usando WHERE
SELECT * FROM table_name WHERE column_name = 'value';- Ordenar por columnas
SELECT * FROM table_name ORDER BY column_name ASC|DESC;- Funciones de Agregación
SELECT COUNT(column_name) FROM table_name;
SELECT AVG(column_name) FROM table_name;
SELECT SUM(column_name) FROM table_name;
SELECT MIN(column_name) FROM table_name;
SELECT MAX(column_name) FROM table_name;- Agrupar por columnas
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column;- Cláusula Having (usada con GROUP BY)
SELECT COUNT(column_name), group_column FROM table_name GROUP BY group_column HAVING COUNT(column_name) > 10;